Commonwealth Professor, Department of Electrical and Computer Engineering
Engineering West Hall, Room 238, Richmond, VA, UNITED STATES
Professor Bandyopadhyay has authored and co-authored nearly 400 research publications
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.
2017-08-23Named 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.
2016-02-15School of Engineering, Virginia Commonwealth University, 2015. One of two such awards given in the department's history.
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.
2012-08-07Given jointly by the College of Engineering, the College of Science, and the Institute for Agricultural and Natural Resources at University of Nebraska-Lincoln
2001-05-01International Business Machines, 1990
1990-06-01College of Engineering, University of Nebraska-Lincoln, 1999
1999-05-15College of Engineering, University of Nebraska Lincoln, 1998
1998-05-15One of seven industry, government and academic leaders worldwide honored with this award in 2016. All are alumni of Indian Institute of Technology, Kharagpur.
2016-07-07Citation: For contributions to device applications of nanostructures
2005-01-01Citation: For pioneering contributions to device applications of nanostructures.
2005-01-01In 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
2006-10-13For outstanding contributions to physics of nanostructured devices.
2005-05-03For pioneering contributions to spintronics and device applications of self assembled nanostructures
2006-10-27The 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.
2018-01-31Ph.D., Electrical Engineering
M.S., Electrical Engineering
B.Tech, Electronics and Electrical Communications Engineering
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.
view moreVirginia 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.”
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
view moreVirginia 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.”
view moreTimes 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.
view moreCommunity 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...
view moreThe 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...
view moreNanoTechWeb
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...
view moreECN 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."
view morePhys.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.
view morePhys.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.
view moreEE 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.
view moreKurzweil 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]
view moreInstitute 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.
view moreNanoScienceWorks 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.
view moreScience 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.
view moreSoftpedia 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
view moreComputer 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.
view moreCIO 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.
view morePhys.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.
view moreEE 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.
view moreLaboratory 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.
view moreThe 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."
view moreNanostructures
2017-01-03
Spintronics is the science and technology of storing, sensing, processing and communicating information with the quantum mechanical spin properties of electrons.
view moreNanomagnets
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.
view moreNanowires
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.
view more9379162
2016-06-28
8946678
2015-02-03
8921962
2014-12-30
6501676
2002-12-31
5747180
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.
view moreNational 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.
State of Virginia Commonwealth Research Commercialization Fund $ 100,000
2017-01-03
This grant is to establish a simulation hub for modeling magnetization dynamics of multiferroic nanomagnets under strain, with a view to applying them for ultra energy efficient computing.
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.
view moreVirginia 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
Introduces graduate students to quantum theory of solids with emphasis on applications in solid state devices.
Introduces advanced graduate students to various facets of spintronics, spin physics, spin devices and elements of spin based quantum computing.
Introduces graduate students to grant writing, paper writing and perfects their skills in oral presentations.
Introduces undergraduates to the physics and operating principles of electronic and optical devices.
2018-09-05
M. A. Abeed, J. Atulasimha and S. Bandyopadhyay
We theoretically study the effect of a material defect (material void) on switching errors associated with magneto-elastic switching of magnetization in elliptical magnetostrictive nanomagnets having in-plane magnetic anisotropy. We find that the error probability increases significantly in the presence of the defect, indicating that magneto-elastic switching is particularly vulnerable to material imperfections. Curiously, there is a critical stress value that gives the lowest error probability in both defect-free and defective nanomagnets. The critical stress is much higher in defective nanomagnets than in defect-free ones. Since it is more difficult to generate the critical stress in small nanomagnets than in large nanomagnets (having the same energy barrier for thermal stability), it would be a challenge to downscale magneto-elastically switched nanomagnets in memory and other applications where reliable switching is required. This is likely to be further exacerbated by the presence of defects
view more2018-08-29
Noel D'Souza, Ayan Biswas, Hasnain Ahmad, Mohammad Salehi Fashami, Md Mamun Al-Rashid, Vimal Sampath, Dhritiman Bhattacharya, Md Ahsanul Abeed, Jayasimha Atulasimha and Supriyo Bandyopadhyay
The need for increasingly powerful computing hardware has spawned many ideas stipulating, primarily, the replacement of traditional transistors with alternate 'switches' that dissipate miniscule amounts of energy when they switch and provide additional functionality that are beneficial for information processing. An interesting idea that has emerged recently is the notion of using two-phase (piezoelectric/magnetostrictive) multiferroic nanomagnets with bistable (or multi-stable) magnetization states to encode digital information (bits), and switching the magnetization between these states with small voltages (that strain the nanomagnets) to carry out digital information processing. The switching delay is ~1 ns and the energy dissipated in the switching operation can be few to tens of aJ, which is comparable to, or smaller than, the energy dissipated in switching a modern-day transistor. Unlike a transistor, a nanomagnet is 'non-volatile', so a nanomagnetic processing unit can store the result of a computation locally without refresh cycles, thereby allowing it to double as both logic and memory. These dual-role elements promise new, robust, energy-efficient, high-speed computing and signal processing architectures (usually non-Boolean and often non-von-Neumann) that can be more powerful, architecturally superior (fewer circuit elements needed to implement a given function) and sometimes faster than their traditional transistor-based counterparts. This topical review covers the important advances in computing and information processing with nanomagnets, with emphasis on strain-switched multiferroic nanomagnets acting as non-volatile and energy-efficient switches—a field known as 'straintronics'. It also outlines key challenges in straintronics.
view more2018-11-23
Sucheta Mondal, Md Ahsanul Abeed, Koustuv Dutta, Anulekha De, Sourav Sahoo, Anjan Barman, and Supriyo Bandyopadhyay
Magnetoelastic (or “straintronic”) switching has emerged as an extremely energy-efficient mechanism for switching the magnetization of magnetostrictive nanomagnets in magnetic memory and logic, and non-Boolean circuits. Here, we investigate the ultrafast magnetodynamics associated with straintronic switching in a single quasielliptical magnetostrictive Co nanomagnet deposited on a piezoelectric Pb(Mg1/3Nb2/3)O3–PbTiO3 substrate using time-resolved magneto-optical Kerr effect (TR-MOKE) measurements. The pulsed laser pump beam in the TR-MOKE plays a dual role: it causes precession of the nanomagnet’s magnetization about an applied bias magnetic field and it also generates surface acoustic waves in the piezoelectric substrate that produce periodic strains in the magnetostrictive nanomagnet and modulate the precessional dynamics. This modulation gives rise to intriguing hybrid magnetodynamical modes in the nanomagnet, with a rich spin-wave texture. The characteristic frequencies of these modes are 5–15 GHz, indicating that strain can affect magnetization in a magnetostrictive nanomagnet in time scales much smaller than 1 ns (∼100 ps). This can enable ∼10 GHz range magnetoelastic nano-oscillators that are actuated by strain instead of a spin-polarized current, as well as ultrafast magnetoelectric generation of spin waves for magnonic logic circuits, holograms, etc.
view more2019-02-01
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.
view more2019-05-24
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.
view more2019-06-01
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.
view more2019-09-06
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.
view more2019-09-10
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.
view more
Social