Supriyo Bandyopadhyay, Ph.D.

Gov. Northam recognizes Outstanding Faculty Award recipients

Augusta Free Press  print

2018-03-02

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

2018-03-01

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

2018-02-07

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

2017-08-25

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

2016-07-12

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  

2016-05-04

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  

2016-02-05

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

NanoTechWeb  

2015-09-23

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

2015-07-09

"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

2015-07-08

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

2014-09-03

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

2011-09-01

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

2011-08-17

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

2011-01-27

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

2008-01-17

“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

2007-03-27

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

2007-03-27

"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

2007-03-23

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

2007-03-20

"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

2007-03-19

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

2000-11-28

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

2000-11-16

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

2000-11-21

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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Supriyo Bandyopadhyay, Ph.D. receives 2020 IEEE Nanotechnology Pioneer Award

Virginia Commonwealth University  online

2020-08-25

Supriyo Bandyopadhyay is the sixteenth recipient of the IEEE Pioneer in Nanotechnology Award which was established in 2007. This is the highest award given by the Nanotechnology Council of the Institute of Electrical and Electronics Engineers. Citation: For pioneering contributions to spintronics and sttaintronics employing nanostructures.

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Announcement of the 2020-2021 Jefferson Science Fellows

National Academies of Sciences, Engineering and Medicine  online

2020-09-10

The 2020-2021 class of Jefferson Science Fellows (JSF) is the 16th class of Fellows selected since the program was established in 2003 as an initiative of the Office of the Science and Technology Adviser to the U.S. Secretary of State. The Jefferson Science Fellows Program is designed to further build capacity for science, technology, and engineering expertise within the U.S. Department of State and U.S. Agency for International Development (USAID).

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Supriyo Bandyopadhyay, PhD, Presented with the Albert Nelson Marquis Lifetime Achievement Award by Marquis Who's Who

Marquis Who's Who  online

2020-10-10

RICHMOND, VA, October 20, 2020 /24-7PressRelease/ -- Marquis Who's Who, the world's premier publisher of biographical profiles, is proud to present Supriyo Bandyopadhyay, PhD, with the Albert Nelson Marquis Lifetime Achievement Award. An accomplished listee, Dr. Bandyopadhyay celebrates many years' experience in his professional network, and has been noted for achievements, leadership qualities, and the credentials and successes he has accrued in his field. As in all Marquis Who's Who biographical volumes, individuals profiled are selected on the basis of current reference value. Factors such as position, noteworthy accomplishments, visibility, and prominence in a field are all taken into account during the selection process.

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Spintronics

Nanostructures

2017-01-03

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

Nanomagnets

2017-01-03

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

Nanowires

2017-01-03

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

9379162

2016-06-28

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

8946678

2015-02-03

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

8921962

2014-12-30

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

6501676

2002-12-31

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

5747180

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.

A Probability Correlator for All-Magnetic Probabilistic Computing

National Science Foundation $500,000

2020-06-01

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.

EAGER: Spintronic extreme sub-wavelength and super-gain active electronically scanned antenna (AESA) enabled by phonon-magnon-plasmon-photon coupling.

National Science Foundation $220000

2022-08-01

A serious shortcoming of conventional antennas is that their efficiencies plummet when they are made much smaller than the wavelength of the electromagnetic radiation they transmit. This is an impediment to building ultra-small antennas that can be medically implanted in a patient or embedded in a stealth device for defense or crime-fighting. This roadblock has been recently overcome by a novel genre of antennas implemented with magnetostrictive nanomagnets built on a piezoelectric substrate. A periodic electric field applied to the substrate periodically strains the nanomagnets, which makes their magnetizations oscillate in time and emit electromagnetic waves. The phenomenon that underlies this effect is phonon-magnon-photon coupling. The efficiencies of these novel antennas were found to exceed the theoretical limits on the efficiencies of traditional antennas by more than 100,000 times. The present research will introduce an additional feature by coupling electric charge oscillations (called plasmons) into the antennas by modifying their structure, which can significantly improve the antenna performance. Moreover, by manipulating the direction of the periodic electric field applied to the substrate, the direction of the strain wave propagating in the substrate can be changed, which may allow capability to steer the radiated electromagnetic beam in space, thereby implementing an active electronically scanned antenna (AESA). These antennas will have the potential to open up many new embedded applications, e.g., medically implanted devices that communicate with external monitors while consuming miniscule amounts of energy, ultra-small stealthy listening devices, personal communicators and wearable electronics. Apart from the fundamental knowledge and technological impact the proposed research will benefit society by producing graduate and undergraduate students trained in nanofabrication, characterization and measurement, as well as in device simulation and design. Particular attention will be paid to entrepreneurship opportunities, increasing K-12 and minority participation through various programs, and educating public through popular lectures and internet blogs.

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Strained topological insulator spin field effect transistor

VCU QUEST Fund $50000

2023-08-01

The ‘transistor’ is a three-terminal electronic device where the current flowing between two of the terminals is varied with a voltage or a current applied to the third terminal. A major drawback of the transistor is its energy-inefficiency, which is a serious shortcoming because 10% of the energy produced in developed nations today is consumed by electronics/computers (i.e., by transistors). By the year 2030, it is expected to balloon to 25%, and by 2050 to nearly 100%, leaving nothing for other infrastructure. This has prompted research in transistor-alternatives (or different avatars of the transistor) that are extremely frugal in their use of energy. Many of them are based on the notion of manipulating the quantum mechanical spin degree of freedom of electrons (instead of the usual charge degree of freedom) to elicit transistor-like functionality. They are called “Spin Field Effect Transistors” or SPINFETs. This proposal is intended to experimentally demonstrate a novel genre of SPINFETs employing strained topological insulators. Topological insulators are a new class of quantum materials (e.g. Bi2Te3, Bi2Se3 etc.) that exhibit topologically protected spin textures and intriguing properties such as spin-momentum locking that are not exhibited by any other class of materials. We have termed this invention the “strained topological insulator spin field effect transistor” (STI-SPINFET). It utilizes spin interference in a topological insulator to realize transistor action. The interference is controlled by applying mechanical strain on the topological insulator using a piezoelectric material integrated with the topological material. A voltage applied to the piezoelectric generates strain in the topological insulator which changes the spin interference within it and that changes the current flowing through it, thereby realizing transistor functionality. This unusual modality of transistor action results in a unique transistor transfer characteristic which makes it possible to implement a frequency multiplier with a single STI-SPINFET. Frequency multipliers are used in myriad communication systems (radar, cell phones, 5G/6G networks) and their function is to increase the frequency of any signal by an arbitrary factor for the purpose of signal modulation/demodulation.

Non-volatile Ultra-Low-Power Magnetic Non-Binary Matrix Multipliers as Hardware Accelerators for Machine Learning and Artificial Intelligence

Virginia Innovation Partnership Corporation $75000

2023-01-01

To commercialize a non-binary all-spin matrix multiplier for deep learning tasks via customer discovery.

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Non-binary all spin matrix multiplier

VCU Commercialization Fund $15000

2023-03-01

To commercialize an all spin matrix multiplier for deep learning and artificial intelligence via specific prototype fabrication.

Ultralow-power straintronic switch implemented with a nanomagnet and a topological insulator for “processor in memory” architectures

Virginia Microelectronics Consortium $33000

2023-06-01

To demonstrate a novel switch implemented with a nanomagnet possessing perpendicular magnetic anisotropy deposited on a topological insulator thin film deposited on a piezoelectric substrate. When the nanomagnet is strained with a voltage applied to the piezoelectric, its anisotropy changes to in-plane and exchange interaction opens up a gap in the topological insulator and changes its resistivity.

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.

Spin Wave Electromagnetic Nano‐Antenna Enabled by Tripartite Phonon‐Magnon‐Photon Coupling

Raisa Fabiha, Jonathan Lundquist, Sudip Majumder, Erdem Topsakal, Anjan Barman, Supriyo Bandyopadhya

2022-02-15

Tripartite coupling between phonons, magnons, and photons in a periodic array of elliptical magnetostrictive nanomagnets delineated on a piezoelectric substrate to form a 2D two-phase multiferroic crystal is investigated. Surface acoustic waves (SAW) (phonons) of 5–35 GHz frequency launched into the substrate cause the magnetizations of the nanomagnets to precess at the frequency of the wave, giving rise to confined spin-wave modes (magnons) within the nanomagnets. The spin waves, in turn, radiate electromagnetic waves (photons) into the surrounding space at the SAW frequency. Here, the phonons couple into magnons, which then couple into photons. This tripartite phonon-magnon-photon coupling is thus exploited to implement an extreme sub-wavelength electromagnetic antenna whose measured radiation efficiency and antenna gain exceed the approximate theoretical limits for traditional antennas of the same dimensions by more than two orders of magnitude at some frequencies. Micro-magnetic simulations are in excellent agreement with experimental observations and provide insight into the spin-wave modes that couple into radiating electromagnetic modes to implement the antenna.

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Acousto‐Plasmo‐Magnonics: Coupling Spin Waves with Hybridized Phonon‐Plasmon Waves in a 2D Artificial Magnonic Crystal Deposited on a Plasmonic Material

Sreya Pal, Pratap Kumar Pal, Raisa Fabiha, Supriyo Bandyopadhyay, Anjan Barman

2023-06-01

Coupling between spin waves (SWs) and other waves in nanostructured media has emerged as an important topic of research because of the rich physics and the potential for disruptive technologies. Herein, a new phenomenon is reported in this family involving coupling between SWs and hybridized phonon-plasmon waves in a 2D periodic array of magnetostrictive nanomagnets deposited on a silicon substrate with an intervening thin film of aluminum that acts as a source of surface plasmons. Hybridized phonon-plasmon waves naturally form in this composite material when exposed to ultrashort laser pulses and they non-linearly couple with SWs to produce a new breed of waves – acousto-plasmo-spin waves that can exhibit a “frequency comb” spanning more than one octave. This phenomenon, that we call acousto-plasmo-magnonics resulting from tripartite coupling of magnons, phonons and plasmons, is studied with time-resolved magneto-optical-Kerr-effect microscopy. The findings also reveal the presence of parametric amplification in this system; energy is transferred from the hybridized phonon-plasmon modes to the acousto-plasmo-spin wave modes to amplify the latter. This opens a path to design novel active metamaterials with tailored and enhanced response. It may enable high-efficiency magneto-mechanical-plasmonic frequency mixing in the GHz−THz frequency regime and provide a unique avenue to study non-linear coupling, parametric amplification, and frequency comb physics.

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Strained topological insulator spin field effect transistor

Supriyo Bandyopadhyay

2023-03-03

The notion of a spin field effect transistor, where transistor action is realized by manipulating the spin degree of freedom of charge carriers instead of the charge degree of freedom, has captivated researchers for at least three decades. These transistors are typically implemented by modulating the spin orbit interaction in the transistor’s channel with a gate voltage, which causes gate-controlled spin precession of the current carriers, and that modulates the channel current flowing between the ferromagnetic source and drain contacts to implement transistor action. Here, we introduce a new concept for a spin field effect transistor which does not exploit spin-orbit interaction. Its channel is made of the conducting surface of a strained three dimensional topological insulator (3D-TI) thin film and the transistor function is elicited by straining the channel region with a gate voltage (using a piezoelectric under-layer) to modify the energy dispersion relation, or the Dirac velocity, of the TI surface states. This rotates the spins of the carriers in the channel and that modulates the current flowing between the ferromagnetic source and drain contacts to realize transistor action. We call it a strained-topological-insulator-spin-field-effect-transistor, or STI-SPINFET. Its conductance on/off ratio is too poor to make it useful as a switch, but it may have other uses, such as an extremely energy-efficient stand-alone single-transistor frequency multiplier.

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A spintronic analog of the Landauer residual resistivity dipole on the surface of a topological insulator containing a line defect

Raisa Fabiha and Supriyo Bandyopadhyay

2022-11-25

The Landauer ‘residual resistivity dipole’ is a well-known concept in electron transport through a disordered medium. It is formed when a defect/scatterer reflects an impinging electron causing negative charges to build up on one side of the scatterer and positive charges on the other. This charge imbalance results in the formation of a microscopic electric dipole that affects the electrical resistivity of the medium. Here, we show that an equivalent entity forms in spin polarized electron transport on the surface of a real topological insulator (TI) such as Bi2Te3 containing a line defect. When electrons reflect from such a scatterer, a local spin imbalance forms owing to spin accumulation on one side and depletion on the other side of the scatterer, resulting in a spin current that flows either in the same or in the opposite direction as the injected spin current, and hence, either decreases or increases the spin resistivity. Spatially varying local magnetic fields appear in the vicinity of the scatter, which will cause transiting spins to precess and emit electromagnetic waves. If the current injected into the TI is an alternating current, then the magnetic field’s polarity will oscillate in time with the frequency of the current and if the spins can follow quasi-statically, then they will radiate electromagnetic waves of the same frequency, thereby making the scatterer act as a miniature antenna.

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A Nonvolatile All-Spin Nonbinary Matrix Multiplier: An Efficient Hardware Accelerator for Machine Learning

Rahnuma Rahman and Supriyo bandyopadhyay

2022-10-27

We propose and analyze a compact and nonvolatile nanomagnetic (all-spin) nonbinary matrix multiplier performing the multiply-and-accumulate (MAC) operation using two magnetic tunnel junctions (MTJs) – one activated by strain to act as the multiplier and the other activated by spin-orbit torque pulses to act as a domain wall (DW) synapse that performs the operation of the accumulator. Each MAC operation can be performed in ∼5 ns and the energy dissipated per operation is ∼500 aJ. This provides a very useful hardware accelerator for machine learning and artificial intelligence tasks that often involve the multiplication of large matrices. The nonvolatility allows the matrix multiplier to be embedded in powerful non-von-Neumann architectures. It also allows all computing to be done at the edge while reducing the need to access the cloud, thereby making artificial intelligence more resilient against cyberattacks.

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Robustness of Binary Stochastic Neurons Implemented With Low Barrier Nanomagnets Made of Dilute Magnetic Semiconductors

Rahnuma Rahman and Supriyo Bandyopadhyay

2022-08-26

Binary stochastic neurons (BSNs) are excellent hardware accelerators for machine learning. A popular platform for implementing them is low- or zero-energy barrier nanomagnets possessing in-plane magnetic anisotropy (e.g., circular disks or quasi-elliptical disks with very small eccentricity). Unfortunately, small geometric variations in the lateral shapes of such nanomagnets can produce large changes in the BSN response times if the nanomagnets are made of common metallic ferromagnets (Co,Ni,Fe) with large saturation magnetization.In addition,the response times become very sensitive to initial conditions, i.e., the initial magnetization orientation. In this letter, we show that if the nanomagnets are made of dilute magnetic semiconductors with much smaller saturation magnetization than common metallic ferromagnets, then the variability in their response times (due to shape variations and variation in the initial condition) is drastically suppressed. This significantly reduces the device-to-device variation, which is a serious challenge for large-scale neuromorphic systems. A simple material choice can, therefore, alleviate one of the most aggravating problems in probabilistic computing with nanomagnets.

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Reflection and refraction of a spin at the edge of a quasi-two-dimensional semiconductor layer (quantum well) and a topological insulator

S Shee, R Fabiha, M Cahay, S Bandyopadhyay

2022-04-18

We derive the reflection and refraction laws for an electron spin incident from a quasi-two-dimensional semiconductor region (with no spin–orbit interaction) on the metallic surface of a topological insulator (TI) when the two media are in contact edge to edge. For a given incident angle, there can generally be two different refraction angles for refraction into the two spin eigenstates in the TI surface, resulting in two different ‘spin refractive indices’ (birefringence) and the possibility of two different critical angles for total internal reflection. We derive expressions for the spin refractive indices and the critical angles, which depend on the incident electron’s energy for given effective masses in the two regions and a given potential discontinuity at the TI/semiconductor interface. For some incident electron energies, there is only one critical angle, in which case 100% spin polarized injection can occur into the TI surface from the semiconductor if the angle of incidence exceeds that critical angle. The amplitudes of reflection of the incident spin with and without spin flip at the interface, as well as the refraction (transmission) amplitudes into the two spin eigenstates in the TI, are derived as functions of the angle of incidence.

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The Strong Sensitivity of the Characteristics of Binary Stochastic Neurons Employing Low Barrier Nanomagnets to Small Geometrical Variations

Rahnuma Rahman and Supriyo Bandyopadhyay

Binary stochastic neurons (BSNs) are excellent activators for machine learning. An ideal platform for implementing them is low- or zero-energy-barrier nanomagnets (LBMs) possessing in-plane anisotropy (e.g., circular or slightly elliptical disks) whose fluctuating magnetization encodes a probabilistic (p-) bit. Here, we show that such a BSN’s activation function, the pinning current (which pins the output to a particular binary state), and the response time – all exhibit strong sensitivity to very slight geometric variations in the LBM’s cross-section. A mere 1% change in the diameter of a circular nanomagnet in any arbitrary direction can alter the response time by a factor of ∼4 at room temperature and a 10% change can alter the pinning current by a factor of ∼2. All this causes large device-to-device variation which is detrimental to integration. we also show that the energy dissipation is lowered but the response time is increased by replacing a circular cross-section with a slightly elliptical one and then encoding the p-bit in the magnetization component along the major axis. Encoding the p-bit in the magnetization component along the minor axis has the opposite effect. The energy-delay-product, however, is relatively independent of whether the cross-section is a circle or an ellipse and which magnetization component encodes the p-bit in the case of the ellipse.

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Magnetic Straintronics: An Energy-Efficient Hardware Paradigm for Digital and Analog Information Processing

Supriyo Bandyopadhyay

2022-11-27

This is a research monograph with eleven chapters dealing with the science and technology of magnetic straintronics.

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Formation of binary magnon polaron in a two-dimensional artificial magneto-elastic crysta

Sudip Majumder, J. L. Drobitch, Supriyo Bandyopadhyay & Anjan Barman

2023-12-01

We observed strong tripartite magnon-phonon-magnon coupling in a two-dimensional periodic array of magnetostrictive nanomagnets deposited on a piezoelectric substrate, forming a 2D magnetoelastic “crystal”; the coupling occurred between two Kittel-type spin wave (magnon) modes and a (non-Kittel) magnetoelastic spin wave mode caused by a surface acoustic wave (SAW) (phonons). The strongest coupling occurred when the frequencies and wavevectors of the three modes matched, leading to perfect phase matching. We achieved this condition by carefully engineering the frequency of the SAW, the nanomagnet dimensions and the bias magnetic field that determined the frequencies of the two Kittel-type modes. The strong coupling (cooperativity factor exceeding unity) led to the formation of a new quasi-particle, called a binary magnon-polaron, accompanied by nearly complete (~100%) transfer of energy from the magnetoelastic mode to the two Kittel-type modes. This coupling phenomenon exhibited significant anisotropy since the array did not have rotational symmetry in space. The experimental observations were in good agreement with the theoretical simulations.

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Increasing Flips per Second and Speed of p-Computers by Using Dilute Magnetic Semiconductors

https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=10265150

2023-12-01

—Probabilistic computing with binary stochastic neurons (BSNs) implemented with low-barrier magnets (LBMs) or zero-energy barrier nanoscale ferromagnets possessing in-plane magnetic anisotropy has emerged as an efficient paradigm for solving computationally hard problems. The fluctuating magnetization of an LBM at room temperature encodes a p-bit,which is the building block of a BSN.Its drawback, however, is that the dynamics of common (transition metal) ferromagnets are relatively slow, and, hence, the number of uncorrelated p-bits that can be generated per second—the so-called “flips per second” (fps)—is insufficient, leading to slow computational speed in autonomous coprocessing with p-computers. Here, we show that a simple way to increase fps in LBMs is to replace commonly used ferromagnets (e.g., Co, Fe, and Ni), which have large saturation magnetization Ms, with a dilute magnetic semiconductor, such as GaMnAs with much smaller saturation magnetization. The smaller Ms reduces any residual energy barrier within an LBM and increases the fps significantly. It also offers other benefits, such as reduced dipole coupling between neighbors, resulting in larger density of uncorrelated p-bits for more processing power, and reduced device-to-device variation. All this provides a way to realize the hardware acceleration and energy efficiency promise of p-computers.

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A Spin Field Effect Transistor Based on a Strained Two Dimensional Layer of a Weyl Semimetal

Rahnuma Rahman and Supriyo Bandyopadhyhay

2023-12-01

Spin field effect transistors (SpinFET) are an iconic class of spintronic transistor devices that exploit gate tuned spin-orbit interaction in semiconductor channels interposed between ferromagnetic source and drain contacts to elicit transistor functionality. Recently, a new and different type of SpinFET based on gate tuned strain in quantum materials (e.g. topological insulators) has been proposed and may have interesting analog applications, such as in frequency multiplication, by virtue of its unusual oscillatory transfer characteristic. Here, we propose and analyze yet another type of SpinFET in this class, which may have a different application. It is based on gate-tuned strain in a Weyl semimetal, with the strain modulating spin interference. Because the operating principle is non-classical, the channel conductance shows oscillatory dependence on the channel length at zero gate voltage. Furthermore, the transconductance can switch sign if the channel length is varied. This latter feature can be exploited to implement a complementary device like complementary metal oxide semiconductor (CMOS) by connecting two such SpinFETs of slightly different channel lengths in series. These unusual properties may have niche applications.

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