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Supriyo Bandyopadhyay, Ph.D. - VCU College of Engineering. Engineering West Hall, Room 238, Richmond, VA, US

Supriyo Bandyopadhyay, Ph.D. Supriyo Bandyopadhyay, Ph.D.

Commonwealth Professor, Department of Electrical and Computer Engineering | VCU College of Engineering

Engineering West Hall, Room 238, Richmond, VA, UNITED STATES

Professor Bandyopadhyay has authored and co-authored nearly 400 research publications



Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication Supriyo Bandyopadhyay, Ph.D. Publication





Supriyo Bandyopadhyay is Commonwealth Professor of Electrical and Computer Engineering at Virginia Commonwealth University. He received a B. Tech degree in Electronics and Electrical Communications Engineering from the Indian Institute of Technology, Kharagpur, India; an M.S degree in Electrical Engineering from Southern Illinois University, Carbondale, Illinois; and a Ph.D. degree in Electrical Engineering from Purdue University, West Lafayette, Indiana. He spent one year as a Visiting Assistant Professor at Purdue University, West Lafayette, Indiana (1986-87) and then nine years on the faculty of University of Notre Dame. In 1996, he joined University of Nebraska-Lincoln as Professor of Electrical Engineering, and then in 2001, moved to Virginia Commonwealth University as a Professor of Electrical and Computer Engineering, with a courtesy appointment as Professor of Physics. He directs the Quantum Device Laboratory in the Department of Electrical and Computer Engineering. Research in the laboratory has been frequently featured in national and international media. Its educational activities were highlighted in a pilot study conducted by the ASME to assess nanotechnology pipeline challenges. The laboratory has graduated many outstanding researchers who have won numerous national and international awards.

Prof. Bandyopadhyay has authored and co-authored nearly 400 research publications and presented nearly 150 invited or keynote talks at conferences and colloquia/seminars across four continents. He is the author of three popular textbooks, including the only English language textbook on spintronics. He is currently a member of the editorial boards of eleven international journals and served in the editorial boards of four other journals in the past. He has served in various committees of over 70 international conferences and workshops. He is the founding Chair of the Institute of Electrical and Electronics Engineers (IEEE) Technical Committee on Spintronics (Nanotechnology Council), and past-chair of the Technical Committee on Compound Semiconductor Devices and Circuits (Electron Device Society). He was an IEEE Electron Device Society Distinguished Lecturer (2005-2012) and is an IEEE Nanotechnology Council Distinguished Lecturer (2016, 2017). He is also a past Vice President of the IEEE Nanotechnology Council and served in the IEEE Fellow Committee (2016-2018). Prof. Bandyopadhyay is the winner of many awards and distinctions.

Industry Expertise (2)



Areas of Expertise (11)

Self-assembly of Regimented Nanostructure Arrays


Quantum Devices

Hot Carrier Transport in Nanostructures


Quantum Computing


Computing Paradigms

Optical Properties of Nanostructures

Coherent spin transport in Nanowires for Sensing and Information Processing

Nanowire-based Room Temperature Infrared Detectors

Accomplishments (16)

University Award of Excellence (professional)


Virginia Commonwealth University faculty award for performing in a superior manner in teaching, scholarly activity and service. One award is given in any year. It is one of the highest awards the University can bestow on a faculty member.

Virginia's Outstanding Scientist (professional)


Named by the Governor of the State of Virginia, 2016. One of two recipients in the State of Virginia. This award is given across all fields of engineering, science, mathematics and medicine.

Electrical and Computer Engineering Lifetime Achievement Award, VCU (professional)

School of Engineering, Virginia Commonwealth University, 2015. One of two such awards given in the department's history.

Distinguished Scholarship Award, Virginia Commonwealth University (professional)


Virginia Commonwealth University, 2012. One award is given in any year and covers all fields of science, humanities, business, education, social science, engineering and medicine.

Interdisciplinary Research Award, University of Nebraska-Lincoln (professional)


Given jointly by the College of Engineering, the College of Science, and the Institute for Agricultural and Natural Resources at University of Nebraska-Lincoln

IBM Faculty Award (professional)


International Business Machines, 1990

College of Engineering Service Award, University of Nebraska-Lincoln (professional)


College of Engineering, University of Nebraska-Lincoln, 1999

College of Engineering Research Award, University of Nebraska-Lincoln (professional)


College of Engineering, University of Nebraska Lincoln, 1998

Distinguished Alumnus Award, Indian Institute of Technology, Kharagpur, India (professional)


One of seven industry, government and academic leaders worldwide honored with this award in 2016. All are alumni of Indian Institute of Technology, Kharagpur.

Fellow of the Institute of Electrical and Electronics Engineers (IEEE) (professional)


Citation: For contributions to device applications of nanostructures

Fellow, American Physical Society (professional)


Citation: For pioneering contributions to device applications of nanostructures.

Fellow of the Electrochemical Society (professional)


In recognition of the contributions to the advancement of science and technology, for leadership in electrochemical and solid state science and technology and for active participation in the affairs of the Electrochemical Society

Fellow of the Institute of Physics (professional)


For outstanding contributions to physics of nanostructured devices.

Fellow of the American Association for the Advancment of Science (professional)


For pioneering contributions to spintronics and device applications of self assembled nanostructures

State Council of Higher Education for Virginia (SCHEV) Outstanding Faculty Award (professional)


The Outstanding Faculty Awards are the Commonwealth's highest honor for faculty at Virginia's public and private colleges and universities. These awards recognize superior accomplishments in teaching, research, and public service.

IEEE Pioneer in Nanotechnology Award (professional)


Citation: For pioneering contributions to spintronics and straintronics employing nanostructures

Education (3)

Purdue University: Ph.D., Electrical Engineering

Southern Illinois University: M.S., Electrical Engineering

Indian Institute of Technology, Kharagpur: B.Tech, Electronics and Electrical Communications Engineering

Affiliations (5)

  • American Physical Society
  • The Electrochemical Society
  • American Association for the Advancement of Science
  • Institute of Electrical and Electronics Engineers: Past Vice President of Nanotechnology Council, Past Associate Editor of IEEE Transactions on Electron Devices, Past Chair of the Technical Committee on Compound Semiconductor Devices and Circuits, Founding Chair of the Technical Committee on Spintronics
  • Institute of Physics (UK): Editorial Board Member of the journals Nanotechnology and Nano Futures

Media Appearances (23)

Gov. Northam recognizes Outstanding Faculty Award recipients

Augusta Free Press  print


Supriyo Bandyopadhyay is commonwealth professor of electrical and computer engineering at Virginia Commonwealth University where he has worked for 17 years as director of the Quantum Device Laboratory. Bandyopadhyay was named Virginia’s Outstanding Scientist by Governor Terry McAuliffe in 2016.

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Governor Northam recognizes outstanding faculty awards recipients

Virginia Secretary of Education  online


RICHMOND - Governor Ralph Northam today recognized 12 Virginia educators as recipients of the 32nd annual Outstanding Faculty Award for excellence in teaching, research, and public service. The annual Outstanding Faculty Award program is administered by the State Council of Higher Education for Virginia (SCHEV) and sponsored by Dominion Energy.

“These outstanding educators have devoted their lives to research and teaching.” said Governor Northam. “Each has a proven track record of academic excellence and giving back to their communities. I am pleased to support these wonderful Virginia teachers and it is my privilege to recognize each of them with the Outstanding Faculty Award.”

The recipients, all faculty members from colleges and universities across the Commonwealth, were honored today during an awards ceremony at the Jefferson Hotel in Richmond.

“The 12 educators that we are recognizing play a pivotal role in the lives and successes of the people they teach and inspire,” said Secretary of Education Atif Qarni. “With this award we thank them for their service to students, to their institutions, and to the Commonwealth.”

“We are fortunate that Virginia is home to one of the world’s great systems of higher education,” said Peter Blake, director of SCHEV. “The Outstanding Faculty Awards recognize faculty members who have dedicated their lives to research, teaching, and mentorship. Their work improves the lives of everyone in the Commonwealth.”

The awards are being made through a $75,000 grant from the Dominion Energy Charitable Foundation, the philanthropic arm of Dominion Energy and the sponsor of the Outstanding Faculty Awards for the 14th year.

“Dominion Energy is pleased to partner with SCHEV once again to honor Virginia’s outstanding educators,” said Hunter A. Applewhite, president of the Dominion Energy Charitable Foundation. “Every year, I am impressed and humbled by the dedication shown by these teachers and researchers to guide and inspire our young people to excel in the classroom and in life.”

VCU Engineering Professor receives Governor's highest award for Teaching

Virginia Commonwealth University  online


Supriyo Bandyopadhyay, Ph.D., Commonwealth Professor in the Virginia Commonwealth University School of Engineering, has been named a recipient of the 2018 State Council of Higher Education for Virginia (SCHEV) Outstanding Faculty Award

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VCU honors six at faculty convocation

Virginia Commonwealth University  online


Bandyopadhyay, named Virginia’s Outstanding Scientist in 2016 by Gov. Terry McAuliffe, leads the Quantum Device Laboratory. His work centers on improving the speed and performance of electronic devices — and lowering their cost. The last piece is very important, Bandyopadhyay said.

“An electronic gadget means absolutely nothing if it is affordable to only a tiny fraction of the world’s population,” he said. “What has motivated, informed and guided my research is to make things cheaper in a more efficient way so they become more accessible. Science is never for the 1 percent; it is always for the 100 percent.”

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IIT-Kharagpur to confer Distinguished Alumnus Award at the 62nd convocation

Times of India  online


Kolkata: Indian Institute of Technology Kharagpur will confer the Distinguished Alumnus Award on the occasion of the 62nd convocation of the Institute which will be organized on July 30 and 31. Seven eminent alumni have been selected for the award for their exceptional professional achievements in the industry, in the academia or as entrepreneur. The awardees are - Dr Anurag Acharya, Ajit Jain, Asoke Deyasarkar, professor Gautam Biswas, professor Indranil Manna, professor Supriyo Bandopadhyay and Professor Venkatesan Thirumalai.

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Putting a New Spin on Electronics

Community Idea Stations  


An international leader in the field of spintronics, Dr. Supriyo Bandyopadhyay directs the Virginia Commonwealth University (VCU) Quantum Device Lab. He was recently named one of Virginia’s Outstanding Scientists by Gov. Terry McAuliffe and the Science Museum of Virginia. This is the first of several articles on all of the 2016 Virginia Outstanding STEM Award winners...

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EVMS diabetes researcher named one of two outstanding scientists of the year in Virginia

The Virginia Pilot  


The other is Dr. Supriyo Bandyopadhyay, a professor in the Department of Electrical and Computer Engineering at Virginia Commonwealth University. His work entails making electronic gadgets out of tiny magnets 1,000 times smaller than the thickness of a human hair. The magnets consume so little energy that they can work without a battery by harvesting energy from wireless networks and wind vibrations...

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Single-electron devices come together



Back in the 1990s, Supriyo Bandyopadhyay, Biswajit Das and Albert Miller at the University of Notre-Dame in France described how to inscribe and manipulate ‘bits’ of logic information in the spin of single electrons. Among the advantages of this computing architecture, they list speed, information density, robustness and power efficiencies. Other groups have also studied how control of single electrons may benefit quantum computing...

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Straintronic spin neuron may greatly improve neural computing

ECN Magazine  online


"Most computers are digital in nature and process information using Boolean logic," Bandyopadhyay told Phys.org. "However, there are certain computational tasks that are better suited for 'neuromorphic computing,' which is based on how the human brain perceives and processes information. This inspired the field of artificial neural networks, which made great progress in the last century but was ultimately stymied by a hardware impasse. The electronics used to implement artificial neurons and synapses employ transistors and operational amplifiers, which dissipate enormous amounts of energy in the form of heat and consume large amounts of space on a chip. These drawbacks make thermal management on the chip extremely difficult and neuromorphic computing less attractive than it should be."

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'Straintronic spin neuron' may greatly improve neural computing

Phys.org  online


Researchers have proposed a new type of artificial neuron called a "straintronic spin neuron" that could serve as the basic unit of artificial neural networks—systems modeled on human brains that have the ability to compute, learn, and adapt. Compared to previous designs, the new artificial neuron is potentially orders of magnitude more energy-efficient, more robust against thermal degradation, and fires at a faster rate.

The researchers, Ayan K. Biswas, Professor Jayasimha Atulasimha, and Professor Supriyo Bandyopadhyay at Virginia Commonwealth University in Richmond, have published a paper on the straintronic spin neuron in a recent issue of Nanotechnology.

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Non-volatile memory improves energy efficiency by two orders of magnitude

Phys.org  online


By using voltage-generated stress to switch between two magnetic states, researchers have designed a new non-volatile memory with extremely high energy efficiency—about two orders of magnitude higher than that of the previous most efficient non-volatile memories.

The engineers, Ayan K. Biswas, Professor Supriyo Bandyopadhyay, and Professor Jayasimha Atulasimha at Virginia Commonwealth University in Richmond, Virginia, have published their paper on the proposed non-volatile memory in a recent issue of Applied Physics Letters.

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Researchers aim for energy-harvesting CPUs

EE Times  online


SAN FRANCISCO—A team of researchers from Virginia Commonwealth University (VCU) was awarded two grants totaling $1.75 million from the U.S. National Science Foundation and the Nanoelectronics Research Initiative of Semiconductor Research Corp. to create powerful, energy-efficient computer processors that can run an embedded system without requiring battery power.

The research, based on a paper published by the VCU research team in the August issue of the journal Applied Physics Letters, replaces transistors with special tiny nanomagnets that can also process digital information, theoretically reducing the heat dissipation by one 1,000 to 10,000 times, according to VCU.

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Hybrid spintronics and straintronics enable ultra-low-energy computing and signal processing

Kurzweil  online


Ref.: Kuntal Roy, Supriyo Bandyopadhyay, and Jayasimha Atulasimha, Hybrid spintronics and straintronics: A magnetic technology for ultra-low-energy computing signal processing, Applied Physics Letters, 2011; [DOI:10.1063/1.3624900]

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Strain and spin could drive ultralow energy computers

Institute of Physics: PhysicsWorld  online


Tiny layered magnets could be used as the basic processing units in highly energy-efficient computers. So say researchers in the US who have shown that the magnetization of these nanometre-sized magnets can be switched using extremely small voltages that induce mechanical strain in a layer of the material. The resulting mechanical deformations affect the behaviour of electron spins, allowing the materials to be used in spintronics devices. These are electronic circuits that exploit the spin of the electron as well as its charge.

Hybrid spintronics/straintronics processors made from such magnets would require very little energy and therefore could work battery-free by harvesting energy from their environment. As a result they could find a host of unique applications, including implantable medical devices and autonomous sensors.

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Dr. Supriyo Bandyopadhyay: Spintronics Drives Next-Gen Computing

NanoScienceWorks  online


“Spin based computers can be powered by small lightweight batteries. I am particularly interested in organic spintronics. Organics can sustain spin memory for very long times and organics can be integrated with flexible substrates. One day that may lead to wearable spin based organic supercomputers housed in a wristwatch and powered by a wristwatch battery,” Dr. Bandyopadhyay told NanoScineceWorks.org.

Dr. Bandyopadhyay also serves as Professor of Electrical Engineering and Professor of Physics at VCU.

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Spintronics: Making Computers Smaller and Faster

Science Daily  online


Researchers have made an important advance in the emerging field of 'spintronics' that may one day usher in a new generation of smaller, smarter, faster computers, sensors and other devices, according to findings reported in today's issue of the journal Nature Nanotechnology.

The research field of 'spintronics' is concerned with using the 'spin' of an electron for storing, processing and communicating information.

The research team of electrical and computer engineers from the Virginia Commonwealth University's School of Engineering and the University of Cincinnati examined the 'spin' of electrons in organic nanowires, which are ultra-small structures made from organic materials. These structures have a diameter of 50 nanometers, which is 2,000 times smaller than the width of a human hair. The spin of an electron is a property that makes the electron act like a tiny magnet. This property can be used to encode information in electronic circuits, computers, and virtually every other electronic gadget.

"In order to store and process information, the spin of an electron must be relatively robust. The most important property that determines the robustness of spin is the so-called 'spin relaxation time,' which is the time it takes for the spin to 'relax.' When spin relaxes, the information encoded in it is lost. Therefore, we want the spin relaxation time to be as long as possible," said corresponding author Supriyo Bandyopadhyay, Ph.D., a professor in the Department of Electrical and Computer Engineering at the VCU School of Engineering.

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Spintronics, the Way to Faster and Smaller Computers

Softpedia News  online


"In order to store and process information, the spin of an electron must be relatively robust. The most important property that determines the robustness of spin is the so-called 'spin relaxation time,' which is the time it takes for the spin to 'relax.' When spin relaxes, the information encoded in it is lost. Therefore, we want the spin relaxation time to be as long as possible," said corresponding author Supriyo Bandyopadhyay, Ph.D., a professor in the Department of Electrical and Computer Engineering

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Researchers spin out smaller electronics than ever before

Computer World  online


A research team of electrical and computer engineers in the U.S. is taking a new approach to electronics that harnesses the spin of an electron to store and process information. Dubbed 'spintronics', the new technology is expected to one day form a basis for the development of smaller, smarter, faster devices.

Current day electronics are predominantly charge-based; that is, electrons are given more or less electric charge to denote the binary bits 0 and 1. Switching between the binary bits is accomplished by either injecting or removing charge from a device, which can, in more resource-intensive applications, require a lot of energy.

"This [energy consumption] is a fundamental shortcoming of all charge based electronics," said lead researcher Supriyo Bandyopadhyay, a professor of Electrical and Computer Engineering at Virginia Commonwealth University.

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Spintronics Research May Lead to Faster Computers

CIO  online


"In order to store and process information, the spin of an electron must be relatively robust. The most important property that determines the robustness of spin is the so-called spin relaxation time, which is the time it takes for the spin to "relax." When spin relaxes, the information encoded in it is lost. Therefore, we want the spin relaxation time to be as long as possible," said corresponding author Supriyo Bandyopadhyay, PhD, a professor in the department of electrical and computer engineering at the VCU School of Engineering.

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Researchers study electron spin relaxation in organic nanostructures

Phys.org  online


Researchers have made an important advance in the emerging field of 'spintronics' that may one day usher in a new generation of smaller, smarter, faster computers, sensors and other devices, according to findings reported in today's issue of the journal Nature Nanotechnology.

The research field of 'spintronics' is concerned with using the 'spin' of an electron for storing, processing and communicating information.

The research team of electrical and computer engineers from the Virginia Commonwealth University’s School of Engineering and the University of Cincinnati examined the ‘spin’ of electrons in organic nanowires, which are ultra-small structures made from organic materials. These structures have a diameter of 50 nanometers. The spin of an electron is a property that makes the electron act like a tiny magnet. This property can be used to encode information in electronic circuits, computers, and virtually every other electronic gadget.

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Researchers improve quantum dot construction

EE Times  online


LINCOLN, Neb. — Fashioning themselves "latter-day Edisons," researchers at the University of Nebraska contend that their architecture for quantum-dot development is 500 percent better than its nearest competition. Quantum-dot devices, which use the quantum nature of electrons to switch between binary states, could be a solution to problems encountered by ever-shrinking conventional transistors.

"We set a world record by demonstrating the largest nonlinear coefficient for a semiconductor quantum dot," said Supriyo Bandyopadhyay, the lead researcher. "Previous architectures have been highly praised for achieving a tiny percent increase, but we got a 500 percent increase with our design.

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Self-assembly route to quantum dots said to be simpler, cheaper than others

Laboratory Network  online


Quantum dots are nanoscale structures that have the potential for use as superdense computer data storage media, highly tunable lasers and nonlinear optical devices. But making them has always been difficult and expensive. At the University of Nebraska, Lincoln (UNL), however, researchers are working on a self-assembling dot production method they say is far simpler and potentially cheaper than standard methods.

The conventional process for making quantum dot structures involves film growth (such as by atomic layer epitaxy or chemical vapor deposition), some type of lithographic patterning, and finally etching, such as by reactive ions. This is a complex series of steps. Now, UNL electrical engineering professor Supriyo Bandyopadhyay believes he's got a better way to make quantum dot structures.

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Quantum Mechanics May Contribute to Military Surveillance

The Daily Nebraskan  online


Quantum dots promise to pave the way for a new world in technology.As minuscule entities that are 10,000 times smaller than the width of a human hair, quantum dots have properties which make them the ideal building blocks for a new quantum computing system.Unlike traditional computers that rely on classical physics, the new generation of computers would operate under the strange and fascinating laws of quantum mechanics."With quantum mechanics it is possible for an entity to coexist in two different states at the same time," said electrical engineering professor Supriyo Bandyopadhyay.The ability to be in two different places simultaneously is known as quantum parallelism."The concept of a parallel existence is difficult to explain," Bandyopadhyay. "It appears very strange and mystical."

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Research Focus (3)




Spintronics is the science and technology of storing, sensing, processing and communicating information with the quantum mechanical spin properties of electrons.

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Straintronics is the technology of rotating the magnetization direction of nanomagnets with electrically generated mechanical stress. It has applications in extremely energy-efficient Boolean and non-Boolean computing.

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Infrared photodetection



Infrared photodetectors have applications in night vision, collision avoidance systems, healthcare, mine detection, monitoring of global warming, forensics, etc. Room temperature detection of infrared light is enabled via quantum engineering in nanowires and by exploiting spin properties of electrons.

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Patents (5)

Magneto-elastic non-volatile multiferroic logic and memory with ultralow energy dissipation



Memory cells, non-volatile logic gates, and combinations thereof have magneto-tunneling junctions (MTJs) which are switched using potential differences across a piezoelectric layer in elastic contact with a magnetostrictive nanomagnet of an MTJ. One or more pairs of electrodes are arranged about the MTJ for supplying voltage across the piezoelectric layer for switching. A permanent magnetic field may be employed to change the positions of the stable magnetic orientations of the magnetostrictive nanomagnet. Exemplary memory cells and universal non-volatile logic gates show dramatically improved performance characteristics, particularly with respect to energy dissipation and error-resilience, over existing methods and architectures for switching MTJs such as spin transfer torque (STT) techniques.

Room temperature nanowire IR, visible and UV photodetectors



Room temperature IR and UV photodetectors are provided by electrochemical self-assembly of nanowires. The detectivity of such IR detectors is up to ten times better than the state of the art. Broad peaks are observed in the room temperature absorption spectra of 10-nm diameter nanowires of CdSe and ZnS at photon energies close to the bandgap energy, indicating that the detectors are frequency selective and preferably detect light of specific frequencies. Provided is a photodetector comprising: an aluminum substrate; a layer of insulator disposed on the aluminum substrate and comprising an array of columnar pores; a plurality of semiconductor nanowires disposed within the pores and standing vertically relative to the aluminum substrate; a layer of nickel disposed in operable communication with one or more of the semiconductor nanowires; and wire leads in operable communication with the aluminum substrate and the layer of nickel for connection with an electrical circuit.

Planar multiferroic/magnetostrictive nanostructures as memory elements, two-stage logic gates and four-state logic elements for information processing



A magnetostrictive-piezoelectric multiferroic single- or multi-domain nanomagnet whose magnetization can be rotated through application of an electric field across the piezoelectric layer has a structure that can include either a shape-anisotropic mangnetostrictive nanomagnet with no magnetocrystalline anisotropy or a circular nanomagnet with biaxial magnetocrystalline anisotropy with dimensions of nominal diameter and thickness. This structure can be used to write and store binary bits encoded in the magnetization orientation, thereby functioning as a memory element, or perform both Boolean and non-Boolean computation, or be integrated with existing magnetic tunneling junction (MTJ) technology to perform a read operation by adding a barrier layer for the MTJ having a high coercivity to serve as the hard magnetic layer of the MTJ, and electrical contact layers of a soft material with small Young's modulus.

Accessing of two-terminal electronic quantum dot comprising static memory



A method of storing and accessing data utiliaing two-terminal static memory cells made from semiconductor quantum dots. Each quantum dot is approximately 10 nm in dimension so as to comprise approximately 1000-10,000 atoms, and each memory cell has in a volume of approximately 6.4×107 cubic Angstroms, thereby corresponding to about 300,000 atoms. In use one of at least two possible stable states is set in the static memory cell by application of a D.C. voltage across the two terminals. The stable state is then monitored by application of A.C. voltage across the two terminals while monitoring the resulting A.C. current flow.

Electrochemical synthesis of quasi-periodic quantum dot and nanostructure arrays


A method of fabricating two-dimensional regimented and quasi periodic arrays of metallic and semiconductor nanostructures (quantum dots) with diameters of about 100 angstroms (10 nm) includes the steps of polishing and anodizing a substrate to form a regimented quasi-periodic array of nanopits. The array forms a template for metallic or semiconductor material. The desired material is deposited in the nanopits by immersing the substrate in an appropriate solution and using the substrate as one cathode and inserting a second cathode in the solution.

Research Grants (7)

Single nanowire spin valve based infrared photodetectors and equality bit comparators

National Science Foundation $425,000


Infrared light is not visible to the human eye. It is usually detected with semiconductor detectors which exhibit a change in their electrical resistance under infrared illumination. The relative change in resistance at room temperature is, however, quite small, which necessitates cooling the detector with liquid nitrogen. In this research, a novel detector will be demonstrated, which relies on light changing the detector's resistance by affecting the quantum mechanical spin properties of the electrons that carry current. With this principle of detection, it is possible to make the resistance change in the detector much larger at room temperature. Room temperature infrared detectors are used in night vision, forensic science, astronomy, missile defense, car-collision avoidance systems and monitoring of global warming, to name a few. Bit comparators are electronic devices that compare two digital (binary) bits of information and render a yes/no decision based on whether the two bits are the same or different. They are important ingredients of electronic circuits and are typically implemented with transistors which cannot remember the decision once the decision has been rendered. A comparator that exploits spin dependent properties and uses magnetic devices instead of transistors can remember the decision and also use less energy. The ability to remember makes it possible to build superior digital electronic circuits that are faster and more error-resilient. In this research, such a comparator will be demonstrated. This project will also integrate research with graduate and undergraduate education, K-12 outreach through the Dean's Early Research Initiative program, and minority enrichment through the Richmond Minorities in Engineering Partnership.

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Energy-efficient strain assisted spin transfer torque memory

National Science Foundation $402392


Non-volatile random access memory (NV-RAM) is often built with a device called spin transfer torque random access memory (STT-RAM), the main constituent of which is a circular nano-magnet. A bit is "written" into the nano-magnet by passing a spin-polarized current whose polarity determines whether bit "1" or bit "0" is written. The energy barrier between these states prevents the magnetization from switching spontaneously due to thermal noise, making the device non-volatile. Unfortunately, the energy dissipated in the writing current is 100-1000 times more than the energy dissipated in today's CMOS devices, which is a large cost to pay for non-volatility. This project seeks to demonstrate that temporarily reducing the energy barrier between the "up" and "down" magnetization states with surface acoustic waves (SAW) can significantly lower the current needed to write a bit and reduce the energy dissipation by orders of magnitude. This would make the SAW-assisted STT-RAM ideal for embedded processors, internet of things, large data centers and cyber-physical systems requiring low energy memory. At least 3 PhD students would be trained on the techniques of complementary nano-fabrication, nano-characterization and computer modeling. The investigators will hold a nano-magnetism workshop for high school students and will host under-represented K-12 students in their labs for a summer month, as well as leverage the "Nano-Days" program to reach out to high school students.

Acquisition of a Physical Properties Measurement System

National Science Foundation $281610


This Major Research Instrumentation award will help acquire a Physical Properties Measurement System (PPMS) with autorotation, supplementary electrical measurements and low and high temperature capabilities coupled with a Vibrating Sample Magnetometer (VSM) at Virginia Commonwealth University (VCU). Additionally, the cryogen-free PPMS/VSM would enable making robust low temperature measurements without requiring liquid helium to extremely sensitive magnetic measurements. The equipment will help enhance research and teaching efforts at VCU and nearby universities including those related to Smart Materials, Electron Theory of Solids, Solid State Physics and Experimental techniques and Foundations of Nanoscience. Improved facilities at VCU will impact high tech skills imparted to both regular and part time students which eventually will help industries located in northeast USA.

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A dual sub-wavelength acoustic and electromagnetic antenna

Virginia Commonwealth University Commercialization Fund $25000


This grant is to develop extreme sub-wavelength acoustic and electromagnetic antennas implemented with nanomagnets actuated by spin orbit torque from a heavy metal nanostrip

A Probability Correlator for All-Magnetic Probabilistic Computing

National Science Foundation $500,000


Probabilistic computing is a computing paradigm that can solve certain problems more efficiently than traditional digital computing. While digital computing deals with deterministic binary bits that are either 0 or 1, probabilistic computing deals with probabilistic (p-) bits that are sometimes 0 and sometimes 1. This is distinct from quantum computing that deals with quantum (qu-) bits which are a superposition of 0 and 1 (and hence a mixture of both 0 and 1 all the time). Quantum computing is more powerful than probabilistic computing, which, in turn, is more powerful than traditional digital computing in many applications. However, quantum computing usually requires the most hardware resources and digital computing the least, with probabilistic computing in-between the two. Most of the hardware resources in probabilistic computing is expended in generating specific correlations between two or more p-bit streams. In this project, we will study and demonstrate a system that will greatly reduce the hardware burden associated with generating correlations. This will be done by using electrically-generated strain in patterned nanomagnetic devices. The results will make probabilistic computing much more efficient than it currently is. The project will educate K-12, undergraduate, and graduate students in this field to increase the pool of skilled scientists and engineers while advancing the field of computing. This work is performed with Prof. Jean-Ann Incorvia from the Department of Electrical Engineering, University of Texas at Austin.

High Power and High Frequency Ultra Miniaturized Extreme Subwavelength Electromagnetic Antenna

Virginia Commonwealth University Commercialization Fund $50000


This project will develop subwavelength electromagnetic antennas implemented with three-phase multiferroics incorporating a ferromagnetic phase, an anti-ferromagnetic phase and a piezoelectric phase. Time varying strain generated in the multiferroic with a surface acoustic wave results in magnetization oscillating that couple to electromagnetic radiation, thereby making the system act as an electromagnetic antenna whose physical dimension is much smaller than the wavelength. This work will build on our past work demonstrating electromagnetic RF antennas based on similar principles whose radiation efficiency beat the theoretical efficiency limits for traditional antennas by more than 5 orders of magnitude. The current work will extend this to X-band microwave and beyond.

EAGER: A Bayesian Network on a Magnetic Tunnel Junction Platform

National Science Foundation $100000


Bayesian networks are a computational model that is very efficient for computing in the presence of uncertainty. It excels in such tasks as predicting stock market behavior, disease progression, etc. It is ideal for taking an event that occurred and predicting the likelihood of different known causes to have been the contributing factor. For example, given the symptoms of a patient, it can compute the probabilities of various diseases that could be causing the symptoms. Unfortunately, implementing Bayesian networks usually requires complex hardware that is expensive, prone to failure, dissipates too much energy and consumes too much area on a computer chip. The goal of this research is to overcome these disadvantages by replacing traditional electronic hardware with magnetic devices that interact with each other in a special way to elicit Bayesian inference. This can reduce the hardware complexity and all associated costs dramatically, making Bayesian networks compact and efficient. This research will establish the viability of this approach through extensive simulations. Graduate students will be trained in this field to produce a pool of skilled scientists and engineers with cutting-edge knowledge.

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Courses (4)

EGRE 620: Electron Theory of Solids

Introduces graduate students to quantum theory of solids with emphasis on applications in solid state devices.

EGRE 621: Introduction to Spintronics

Introduces advanced graduate students to various facets of spintronics, spin physics, spin devices and elements of spin based quantum computing.

EGRE 610: Research Practices in Electrical and Computer Engineering

Introduces graduate students to grant writing, paper writing and perfects their skills in oral presentations.

EGRE 303: Solid State Devices

Introduces undergraduates to the physics and operating principles of electronic and optical devices.

Selected Articles (15)

Low Power Restricted Boltzmann Machine Using Mixed-Mode Magneto-Tunneling Junctions IEEE Electron Device Letters

Shamma Nasrin ; Justine L. Drobitch ; Supriyo Bandyopadhyay ; Amit Ranjan Trivedi


This letter discusses mixed-mode magneto tunneling junction (m-MTJ)-based restricted Boltzmann machine (RBM). RBMs are unsupervised learning models, suitable for extracting features from high-dimensional data. The m-MTJ is actuated by the simultaneous actions of voltage-controlled magnetic anisotropy and voltage-controlled spin-transfer torque, where the switching of the free-layer is probabilistic and can be controlled by the two. Using m-MTJ-based activation functions, we present a novel low area/power RBM. We discuss online learning of the presented implementation to negate process variability. For MNIST hand-written dataset, the design achieves ~96% accuracy under expected variability in various components.

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Microwave Oscillator Based on a Single Straintronic Magnetotunneling Junction Phys. Rev. Applied 11, 054069

Md Ahsanul Abeed, Justine L. Drobitch, and Supriyo Bandyopadhyay


There is growing interest in exploring nanomagnetic devices as potential replacements for electronic devices (e.g., transistors) in digital switching circuits and systems. A special class of nanomagnetic devices are switched with electrically generated mechanical strain leading to electrical control of magnetism. Straintronic magnetotunneling junctions (SMTJs) belong to this category. Their soft layers are composed of two-phase multiferroics comprising a magnetostrictive layer elastically coupled to a piezoelectric layer. Here, we show that a single straintronic magnetotunneling junction with a passive resistor can act as a microwave oscillator whose traditional implementation would have required microwave operational amplifiers, capacitors, and resistors. This reduces device footprint and cost, while improving device reliability. This is an analog application of magnetic devices where magnetic interactions (interaction between the shape anisotropy, strain anisotropy, dipolar coupling field, and spin-transfer torque in the soft layer of the SMTJ) are exploited to implement an oscillator with reduced footprint.

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Low energy barrier nanomagnet design for binary stochastic neurons: Design challenges for real nanomagnets with fabrication defects IEEE Magnetics Letters

Md Ahsanul Abeed and Supriyo Bandyopadhyay


Much attention has been focused on the design of low energy barrier nanomagnets (LBMs), whose magnetizations vary randomly in time owing to thermal noise, for use in binary stochastic neurons (BSNs) that serve as hardware accelerators for machine learning. The performance of BSNs depends on two important parameters: the correlation time τ c associated with the random magnetization dynamics in an LBM, and the spin-polarized pinning current I p , which stabilizes the magnetization of an LBM in a chosen direction within a chosen time. We show that common fabrication defects in LBMs make these two parameters unpredictable because they are strongly sensitive to the defects. That makes the design of BSNs with real LBMs very challenging. Unless the LBMs are fabricated with extremely tight control, the BSNs that use them could be unreliable or suffer from poor yield.

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Reliability of Magnetoelastic Switching of Nonideal Nanomagnets with Defects: A Case Study for the Viability of Straintronic Logic and Memory Physical Review Applied

D. Winters, M. A. Abeed, S. Sahoo, A. Barman and S. Bandyopadhyay


Magnetoelastic (straintronic) switching of bistable magnetostrictive nanomagnets is an extremely energy-efficient switching methodology for (magnetic) binary switches that has recently attracted widespread attention because of its potential application in ultra-low-power digital computing hardware. Unfortunately, this modality of switching is also very error prone at room temperature. Theoretical studies of switching error probability of magnetoelastic switches have predicted probabilities ranging from 10−8 to 10−3 at room temperature for ideal, defect-free nanomagnets, but experiments with real nanomagnets show a much higher probability that exceeds 0.1 in some cases. The obvious spoilers that can cause this large difference are defects and nonidealities. We theoretically study the effect of common defects (that occur during fabrication) on magnetoelastic switching probability in the presence of room-temperature thermal noise. Surprisingly, we find that even small defects increase the switching error probabilities by orders of magnitude. There is usually a critical stress that leads to the lowest error probability and its value increases enormously in the presence of defects. All this could limit or preclude the application of magnetoelastic (straintronic) binary switches in either Boolean logic or memory, despite their excellent energy efficiency, and restrict them to non-Boolean (e.g., neuromorphic, stochastic) computing applications. We also study the difference between magnetoelastic switching with a stress pulse of constant amplitude and sinusoidal time-varying amplitude (e.g., due to a surface acoustic wave) and find that the latter method is more reliable and generates lower switching error probabilities in most cases provided the time variation is reasonably slow.

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Review: Voltage induced strain control of magnetization: computing and other applications Multiferroic Materials

Dhritiman Bhattacharya, Supriyo Bandyopadhyay, Jayasimha Atulasimha


Strain and acoustic waves provide extremely energy efficient means to control magnetization in nanoscale and microscale magnetostrictive materials and devices. This could enable a myriad of applications, such as non-volatile memory, neuromorphic computing, microfluidics, microscale and nanoscale motors, and the generation of electromagnetic waves with sub-wavelength antenna. In this review, we discuss the developments in control of magnetism at the micro and nanoscale with strain, as well as its potential applications in computing and other emerging areas.

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Sensitivity of the Power Spectra of Thermal Magnetization Fluctuations in Low Barrier Nanomagnets Proposed for Stochastic Computing to In-Plane Barrier Height Variations and Structural Defects SPIN

Md Ahsanul Abeed and Supriyo Bandyopadhyay


Nanomagnets with small in-plane shape anisotropy energy barriers on the order of the thermal energy have unstable magnetization that fluctuates randomly in time. They have recently emerged as promising hardware platforms for stochastic computing and machine learning because the random magnetization states can be harnessed for probabilistic bits. Here, we have studied how the statistics of the magnetization fluctuations (e.g., the power spectral density) is affected by (i) moderate variations in the barrier height of the nanomagnet (caused by small size variations) and (ii) the presence of structural defects — both localized and delocalized — in order to assess how robust the stochastic computing platform based on Low Barrier Nanomagnets (LBM) is. We found that the power spectral density is relatively insensitive to moderate barrier height change and also relatively insensitive to the presence of small localized defects. However, extended (delocalized) defects, such as thickness variations over a significant fraction of the nanomagnet, affect the power spectral density very noticeably. That means extended defects can significantly alter the fluctuation rate of the magnetization in low barrier nanomagnets. Since the fluctuation rate is crucial for stochastic computing applications, this has very serious implications for the latter. Thickness variations are difficult to avoid in real nanomagnets with in-plane anisotropy since they must be thin to keep the barrier height small and the substrate on which they are fabricated may have surface roughness comparable to the nanomagnet thickness. This raises questions about the viability of stochastic computing with low barrier nanomagnets possessing in-plane anisotropy. Our results establish that small variations in the shape (causing small variations in the barrier height), or small localized defects, are relatively innocuous and tolerable but extended defects are not. The latter must be avoided for stochastic computing applications.

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The effect of material defects on resonant spin wave modes in a nanomagnet Scientific Reports

Md Ahsanul Abeed, Sourav Sahoo, David Winters, Anjan Barman & Supriyo Bandyopadhyay


We have theoretically studied how resonant spin wave modes in an elliptical nanomagnet are affected by fabrication defects, such as small local thickness variations. Our results indicate that defects of this nature, which can easily result from the fabrication process, or are sometimes deliberately introduced during the fabrication process, will significantly alter the frequencies, magnetic field dependence of the frequencies, and the power and phase profiles of the resonant spin wave modes. They can also spawn new resonant modes and quench existing ones. All this has important ramifications for multi-device circuits based on spin waves, such as phase locked oscillators for neuromorphic computing, where the device-to-device variability caused by defects can be inhibitory.

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Reliability and Scalability of p-Bits Implemented With Low Energy Barrier Nanomagnets IEEE MAGNETICS LETTERS

Justine L. Drobitch and Supriyo Bandyopadhyay


Probabilistic bits (p-bits) implemented with low energy barrier nanomagnets (LBMs) have recently gained
attention because they can be leveraged to perform some computational tasks very efficiently. Although more error resilient than Boolean computing, p-bit-based computing employing LBMs is, however, not completely immune to defects and device-to-device variations. In some tasks (e.g., binary stochastic neurons for machine learning and p-bits for population coding), extended defects, such as variation of the LBM thickness over a significant fraction of the surface, can impair
functionality. We examine if unavoidable geometric device-to-device variations can have a significant effect on one of the most critical requirements for probabilistic computing: the ability to “program” probability with an external agent, such as a spin-polarized current injected into the LBM. We found that the programming ability is fortunately not lost with reasonable device-to-device variations. The little variation in the probability-versus-current characteristic caused by typical device variability can be suppressed further by increasing the spin polarization of the current. This shows that probabilistic
computing with LBMs is resistant against small geometric variations, and hence will be scalable to a large number of p-bits.

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Effect of CoFe dusting layer and annealing on the magnetic properties of sputtered Ta/W/CoFeB/CoFe/MgO layer structures Journal of Physics D: Applied Physics

J L Drobitch, Y-C Hsiao, H Wu, K L Wang, C S Lynch, K Bussmann, S Bandyopadhyay and D B Gopman


We explored the effect of a CoFe wedge inserted as a dusting layer (0.2 nm–0.4 nm thick) at the CoFeB/MgO interface of a sputtered Ta(2 nm)/W(3 nm)/CoFeB(0.9 nm)/MgO(3 nm)/Ta(2 nm) film—a typical structure for spin-orbit torque devices. Films were annealed at
temperatures varying between 300 °C and 400 °C in an argon environment. Ferromagnetic resonance studies and vibrating sample magnetometry measurements were carried out to estimate the effective anisotropy field, the Gilbert damping, the saturation magnetization and the dead layer thickness as a function of the CoFe thickness and across several annealing temperatures. While the as-deposited films present only easy-plane anisotropy, a transition along the wedge from in-plane to out-of-plane was observed across several annealing
temperatures, with evidence of a spin-reorientation transition separating the two regions.

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Spin Transport in Nanowires Synthesized Using Anodic Nanoporous Alumina Films Multilayer Thin Films-Versatile Applications for Materials Engineering, Ed. S. Basu, InTech Open

Supriyo Bandyopadhyay


Spin transport in restricted dimensionality structures (e.g., nanowires) have unusual features not observed in bulk samples. One popular method to synthesize nanowires of different materials is to electrodeposit them selectively within nanometer diameter pores in anodic alumina films. Different materials can be sequentially deposited within the pores to form nanowire “spin valves” consisting of a spacer nanowire sandwiched between two ferromagnetic nanowires. This construct allows one to study spin transport in the spacer nanowire, with the ferromagnetic contacts acting as spin injector and detector. Some of our past work related to the study of spin transport in organic and inorganic nanowire spin valves produced using nanoporous anodic alumina films is reviewed in this chapter.

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Experimental Demonstration of an Extreme Subwavelength Nanomagnetic Acoustic Antenna Actuated by Spin–Orbit Torque from a Heavy Metal Nanostrip Advanced Materials Technologies

Md Ahsanul Abeed and Supriyo Bandyopadhyay


A novel on-chip extreme sub-wavelength “acoustic antenna” whose radiation efficiency is ~50 times larger than the theoretical limit for a resonantly driven antenna is demonstrated. The antenna is composed of magnetostrictive nanomagnets deposited on a piezoelectric substrate. The nanomagnets are partially in contact with a heavy metal (Pt) nanostrip. Passage of alternating current through the nanostrip exerts alternating spin–orbit torque on the nanomagnets and periodically rotates their magnetizations. During the rotation, the magnetostrictive nanomagnets expand and contract, thereby setting up alternating tensile and compressive strain in the piezoelectric substrate underneath. This leads to the generation of a surface acoustic wave in the substrate and makes the nanomagnet assembly act as an acoustic antenna. The measured radiation efficiency of this acoustic antenna at the detected frequency is ~1%, while the wavelength to antenna dimension ratio is ~67:1. For a standard antenna driven at acoustic resonance, the efficiency would have been limited to ~(1/67)^2 = 0.02%. It became possible to beat that limit (by ~50 times) via actuating the antenna not at acoustic resonance, but by using a completely different mechanism involving spin–orbit torque originating from the giant spin Hall effect in Pt.

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Extreme Subwavelength Magnetoelastic Electromagnetic Antenna Implemented with Multiferroic Nanomagnets Advanced Materials Technologies

Justine Lynn Drobitch, Anulekha De, Koustuv Dutta, Pratap Kumar Pal, Arundhati Adhikari, Anjan Barman and Supriyo Bandyopadhyay


Antennas typically have emission/radiation efficiencies bounded by A /λ^2 (A < λ^2) where A is the emitting area and λ is the emitted wavelength. That makes it challenging to miniaturize antennas to extreme subwavelength dimensions without severely compromising their efficiencies. To overcome this challenge, an electromagnetic (EM) antenna is actuated with a surface acoustic wave (SAW) whose wavelength is about five orders of magnitude smaller than the EM wavelength at the same frequency. This allows to implement an extreme subwavelength EM antenna, radiating an EM wave of wavelength λ = 2 m, whose emitting area is ≈10^−8 m2 (A /λ^2 = 2.5 × 10^−9), and whose measured radiation efficiency exceeds the A /λ^2 limit by over 10^5. The antenna consists of magnetostrictive nanomagnets deposited on a piezoelectric substrate. A SAW launched in the substrate with an alternating electrical voltage periodically strains the nanomagnets and rotates their magnetizations owing to the Villari effect. The oscillating magnetizations emit EM waves at the frequency of the SAW. These extreme subwavelength antennas that radiate with efficiencies a few orders of magnitude larger than the A /λ^2 limit allow drastic miniaturization of communication systems.

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Simulated annealing with surface acoustic wave in a dipole-coupled array of magnetostrictive nanomagnets for collective ground state computing Journal of Physics D: Applied Physics

Md Ahsanul Abeed and Supriyo Bandyopadhyay


There is significant current interest in using arrays of interacting nanomagnets as efficient hardware platforms to solve difficult computational problems such as image processing or combinatorial optimization. Problem variables are encoded in the magnetization states of the nanomagnets and the array is allowed to relax to the ground state wherein the magnetic order represents the solution to the problem. This strategy is energy-frugal and ultrafast since it does not involve software (executing instruction sets), but unfortunately, it fails if the system gets stuck in a metastable state
from which it cannot escape to the ground state. Here, we demonstrate, in a small system of dipole-coupled 3 x 3 arrayof magnetostrictive nanomagnets fabricated on a piezoelectric substrate, how the system can be driven out of the metastable state into the ground state with a surface acoustic wave. This process emulates “simulated annealing” which is a well-known algorithm of finding the optimal solution of a function (representing the ground state) by driving the function out of a sub-optimal solution (representing a metastable state) by following a sequence of steps.

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Electrically programmable probabilistic bit anti-correlator on a nanomagnetic platform Scientific Reports, 10, 12361

Mason T. McCray, Md Ahsanul Abeed and Supriyo Bandyopadhyay


Execution of probabilistic computing algorithms require electrically programmable stochasticity to encode arbitrary probability functions and controlled stochastic interaction or correlation between probabilistic (p-) bits. The latter is implemented with complex electronic components leaving a large footprint on a chip and dissipating excessive amount of energy. Here, we show an elegant implementation with just two dipole-coupled magneto-tunneling junctions (MTJ), with magnetostrictive soft layers, fabricated on a piezoelectric film. The resistance states of the two MTJs (high or low) encode the p-bit values (1 or 0) in the two streams. The first MTJ is driven to a resistance state with desired probability via a current or voltage that generates spin transfer torque, while the second MTJ’s resistance state is determined by dipole coupling with the first, thus correlating the second p-bit stream with the first. The effect of dipole coupling can be varied by generating local strain in the soft layer of the second MTJ with a local voltage (~ 0.2 V) and that varies the degree of anti-correlation between the resistance states of the two MTJs and hence between the two streams (from 0 to 100%). This paradigm generates the anti-correlation with “wireless” dipole coupling that consumes no footprint on a chip and dissipates no energy, and it controls the degree of anti-correlation with electrically generated strain that consumes minimal footprint and is extremely frugal in its use of energy. It can be extended to arbitrary number of bit streams. This realizes an “all-magnetic” platform for generating correlations or anti-correlations for probabilistic computing. It also implements a simple 2-node Bayesian network.

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The Many Facets of Nanotechnology IEEE NANO Magazine

Supriyo Bandyopadhyay


This is a popular article on nanotechnology written for the layperson at the invitation of IEEE NANO Magazine

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