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.

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

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.”

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.

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...

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...

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...

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."

'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.

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.

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.

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]

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.

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.

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.

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

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.

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.

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.

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.

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.

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."

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.

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).

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.

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.

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.

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

9379162

2016-06-28

Room temperature nanowire IR, visible and UV photodetectors

8946678

2015-02-03

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

8921962

2014-12-30

Accessing of two-terminal electronic quantum dot comprising static memory

6501676

2002-12-31

Electrochemical synthesis of quasi-periodic quantum dot and nanostructure arrays

5747180

Single nanowire spin valve based infrared photodetectors and equality bit comparators

National Science Foundation $425,000

2017-01-04

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.

Energy-efficient strain assisted spin transfer torque memory

National Science Foundation $402392

2018-05-21

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

2017-08-21

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.

A dual sub-wavelength acoustic and electromagnetic antenna

Virginia Commonwealth University Commercialization Fund $25000

2019-06-01

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

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.

High Power and High Frequency Ultra Miniaturized Extreme Subwavelength Electromagnetic Antenna

Virginia Commonwealth University Commercialization Fund $50000

2020-07-10

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

2020-07-30

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.

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.

2020-01-15

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.

2020-02-10

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.

2020-06-24

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.

2020-06-20

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.

2020-07-19

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.

2020-07-22

Supriyo Bandyopadhyay

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

2020-08-04

Supriyo Bandyopadhyay

The search for a binary switch that is more energy-efficient than a transistor has led to many ideas, notable among which is the notion of using a nanomagnet with two stable magnetization orientations that will encode the binary bits 0 and 1. The nanomagnet is switched between these two orientations (states) with electrically generated mechanical strain. A tiny amount of voltage is required for switching, with energy dissipation on the order of a few to few tens of aJ. Logic gates and memory, predicated on this technology, have been demonstrated in our group. While they indeed dissipate very little energy, they are unfortunately plagued by unacceptably high switching error probability that hinders their application in most types of Boolean logic. Fortunately, they can still be used in applications that are more forgiving of switching errors, e.g. probabilistic computing, analog arithmetic circuits, belief networks, artificial neurons, restricted Boltzmann machines, image processing, and others where the collective activity of many devices acting cooperatively elicit the computing or signal processing function and the failure of a single or few devices does not matter critically. These ultra-energy-efficient strain-switched nanomagnets can also be used for non-computing devices such as microwave oscillators that perform better than spin-torque-nano-oscillators. This short review provides an introduction to this exciting burgeoning field.