Meeting future computing needs requires new materials and phenomena that can overcome barriers to current technologies that are approaching their fundamental limits. Today’s microelectronics use the electron’s charge to encode and manipulate information, but the electron’s spin degree of freedom is emerging as a source of untapped potential for low-power, high-performance computing.
Advances in materials science and engineering are key components of the innovation process. In this four-part series we highlight areas of materials research driving breakthroughs in technology.
Each 2-hour webinar will feature two faculty speakers who will provide complementary perspectives on technology challenges and opportunities and provide an overview of related research activities at MIT. Ten students will also give short presentations on their recent research results, followed by parallel break-out sessions for detailed discussions.
Jewan John Bae comes to MIT Corporate Relations with more than 20 years of experience in the specialty chemicals and construction industries. He facilitates fruitful relationships between MIT and the industry, engaging with executive level managers to understand their business challenges and match them with resources within the MIT innovation ecosystem to help meet their business objectives.
Bae’s areas of expertise include new product commercialization stage gate process, portfolio management & resource planning, and strategic planning. He has held various business leadership positions at W.R. Grace & Co., the manufacturer of high-performance specialty chemicals and materials, including Director of Strategic Planning & Process, Director of Sales in the Americas, and Global Strategic Marketing Director. Bae is a recipient of the US Army Commendation Medal in 1986.
Professor Thompson joined the MIT faculty in 1983. He is Director of MIT’s Materials Research Laboratory and co-Director of the Skoltech Center for Electrochemical Energy Storage. His research interests include processing of thin films and nanostructures for applications in microelectronic, microelectromechanical, and electrochemical systems. Current activities focus on development of thin film batteries for autonomous microsystems, IC interconnect and GaN-based device reliability, and morphological stability of thin films and nano-scale structures. Thompson holds an SB in materials science and engineering from MIT and a PhD in applied physics from Harvard University.
Professor Geoffrey Beach worked in UCSD's Center for Magnetic Recording Research to develop novel magnetic thin-film nanocomposites for ultrafast data storage applications. He later went on to the University of Texas at Austin as a Postdoctoral Fellow in the Department of Physics and the Texas Materials Institute where he made important discoveries in magnetization dynamics and spin-transfer torque in nanoscale magnetic structures. His current research interests focus on spin dynamics and “spin-electronics” in nanoscale magnetic materials and devices. Developing ways to store information more densely and to access it more quickly requires understanding the magnetization configurations in nanoscale structures and how they evolve in time. His work aims in part to understand and control spin excitations in magnetic materials whose dimensions approach fundamental magnetic length scales. One of the most exciting prospects in magnetism today is the possibility of electrical control of the magnetic state of a device, taking advantage of the coupling between spin and charge in a conducting ferromagnetic material. A major thrust of his research aims to harness the spin of the electron in magnetic materials to realize new approaches to spin-based storage and computation. Studying these processes requires the development of advanced instrumentation capable of probing magnetization dynamics at the shortest timescales and the smallest length scales. His group will work to develop new optical and electrical approaches to push the detection limits in order to enable development of new materials and structures to meet the information storage and processing demands of the future.
A major obstacle for future progress in microelectronics is reducing power consumption. Devices that exploit the electron spin degree of freedom together with, or instead of, its charge, provide a pathway to meet this challenge. Solid-state spin-based devices have already entered the marketplace for nonvolatile memory applications, and the door to broader computing applications is now open. In this talk I will describe recently-discovered mechanisms, materials, and devices that offer a spin-based approach to augment conventional electronics as current technologies approach the end of their roadmap.
Professor Marc A. Baldo is a principal investigator in the Research Laboratory of Electronics (RLE) at the Massachusetts Institute of Technology (MIT). Professor Baldo’s research interests include molecular electronics, electrical and exciton transport in organic materials, energy transfer, metal-organic contacts, heterogeneous integration of biological materials, and novel organic transistors.
Professor Baldo received his B. Eng. (Electrical Engineering) from the University of Sydney in 1995 with first class honors and university medal, and his M.A. and Ph.D. from Princeton in 1998 and 2001, respectively. In 2002 he joined MIT as an Assistant Professor of Electrical Engineering. In 2004, he was appointed Esther and Harold E. Edgerton Assistant Professor of Electrical Engineering.
New architectures for computation offer performance advantages for specific applications such as optimization and machine learning. In this talk, I will discuss the potential benefits of spintronics, with a focus at the system level. Collective switching of multiple spins promises to reduce the power delay product relative to conventional field effect transistors. But spintronic phenomena can also be exploited to realize novel devices such as programmable nonlinear function evaluators and coupled oscillators, providing potential benefits beyond traditional von Neumann architectures.
As part of the program for this webinar, we are offering breakout discussions with our presenting graduate students and postdocs. In order to participate in these breakout rooms, you will need the latest version of Zoom (version 5.3.2). (If you need help determining your version of Zoom, please follow the instructions here.)
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Topic/ Invited Presenter/Position
Title and Abstract
Spin hall materials/devices and magnonics
Gated nonreciprocal magnon transmission from direction-dependent magnetic damping
An important application of magnetic materials in information processing and communication is to provide nonreciprocity. Conventional ferromagnet-based microwave circulators and optical isolators suffer from their bulk volume and the difficulty of being integrated into high-density circuits. We show that in an on-chip device with a magnetic gate, tunable nonreciprocal propagation can be realized in spin Hall effect-excited magnons with broadband spectrum. We identify a direction-dependent magnetic damping as the origin of the nonreciprocity. Our findings provide a general mechanism for introducing directional magnon transmission and lead to a design of passively gated magnon transistors for emergent chiral magnonic applications.
Prof. Luqiao Liu
Current-induced Switching of Compensated Ferrimagnets and Antiferromagnets
Magnetic random access memories (MRAMs) using compensated ferrimagnets or antiferromagnets as free layers have great potentials of higher density, speed, and power efficiency. The advantages come from the fully compensated magnetic moments, allowing zero stray field and faster magnetic dynamics. Spin-orbit torque, an efficient way to switch ferromagnetic memory bits, may also switch compensated ferrimagnets and antiferromagnets efficiently. For compensated ferromagnets, we demonstrated the spin-orbit torque switching first in Co1-xTbx alloy, and then in Mn2Ru1−xGa, a Heusler alloy with lower damping and higher spin polarization. Furthermore, we clarified the complicated mechanisms of the current-induced switching in the canted antiferromagnet α-Fe2O3.
Spin currents in insulators
Magnetic and spintronic properties of Y-substituted TmIG thin films
Thulium iron garnet (TmIG) has excited great interest due to record-breaking spin orbit torque-driven domain wall velocities over 2 km/s and the presence of the Dzyaloshinskii-Moriya interaction, which stabilizes chiral Néel domain walls. In this study we describe the static and dynamic magnetic properties of yttrium-substituted TmIG (TmYIG) thin films with a variety of Y:Tm ratios grown by pulsed laser deposition. We find that, by varying the Y:Tm ratio over a range of 0-0.67, we can tune the anisotropy energy of the film over three orders of magnitude and observe a transition from PMA to in-plane anisotropy with little change in room temperature magnetization. We relate the anisotropy to the changes in both magnetostriction and strain state vs. composition.
Prof. Caroline Ross
Voltage controlled magnetism
Voltage-controlled ON/OFF magnetism above room temperative in SrCo1-xFexO3-δ
Searching for new materials and phenomena to enable voltage control of magnetism and magnetic properties holds compelling interest for the development of low-power nonvolatile memory devices. Here, I will present a voltage control of magnetism in epitaxial SrCo1−xFexO3−δ (SCFO). For the Co/Fe ratio of ∼1:1, a switch between nonmagnetic (OFF) and ferromagnetic (ON) states is accomplished by ionic liquid gating at ambient conditions with voltages as low as ±2 V. Tuning the oxygen stoichiometry enables reversible and continuous control of the magnetization between 0 and 100 emu/cm3 at room temperature.
Quantum Materials for Future Spintronics
Surface/Interface Driven Novel Topological Phenomena
Surfaces/interfaces are pivotal for uncovering novel physical phenomena and functionalities. Understanding their complex behavior, especially in exchange coupled systems, is essential for advancing spintronics. Structures hybridizing topological insulators (TIs) with ferromagnetism are particularly promising for exploiting correlated interactions originated from the electrostatic and quantum mechanical nature of the exchange coupling. Owing to time-reversal symmetry breaking, exchange gap opens in the Dirac surface states of TI, enabling dissipationless chiral transport with full spin polarization. The unique spin-momentum locking feature of the surface Dirac fermions also bode well for unprecedented magnetoelectric properties in hybrid structures for tuning the magnetism via electrostatic means.
Prof. Jagadeesh Moodera
Correlated magnetic phenomena in quantum materials
Coexistence of dirac electrons and magnetism in Fe-based kagome metals.
Spin-orbit coupled Dirac electronic states in topological insulators have shown significant promise as a source of spin currents including enabling efficient magnetization switching when interfaced with a ferromagnet. We discuss the diverse set of behaviors in the Fe-based kagome lattice which allows Dirac electrons and room temperature magnetism to coexist in a single material platform. The ferromagnetic kagome metal Fe3Sn2 hosts a gapped Dirac band in the bulk and spin-polarized dissipationless current circulating at its boundaries, transporting high fidelity spin information with zero power consumption. Alternatively, the antiferromagnetic kagome metal FeSn, consisting of an alternating stack of magnetic Fe-layer and heavy mass Sn-layer offers a natural atomic scale heterostructure that can be integrated into antiferromagnetic spintronic devices.
Prof. Joe Checkelsky
Materials for energy efficient computing
Antiferromagnetic spintronics for memory technology
The development of charge-based devices is fast approaching its limits according to Moore's law-driven International Technology Roadmap for Semiconductors. Spintronics is among the most frequently mentioned alternatives. The pressing task of improving performances has recently led to a growing interest in alternative magnetically ordered systems such as antiferromagnets (AFMs), as they offer the prospect of non-volatility and radiation hardness on a nanoscale combined with ultrafast spin-dynamics in the THz frequency range. The breakthrough in this field was the recent realization of electrical control of the Néel-vector revealing the high potential of AFMs for application in memory technology.
Prof. Geoffrey Beach
Strengths and limitations of thin film ferrimagnetic bubble skyrmions
Magnetic skyrmions are nanoscale magnetic quasi-particles whose spin structure can be mapped continuously on a sphere. They are promising candidates for future spintronic devices such as the skyrmion racetrack memory and can be readily stabilized in interfacial thin film materials, which may exhibit efficient spin dynamics, making these systems extremely promising for applications. Here, we will discuss recent advances in the field of skyrmionics and how the performance of skyrmion-based devices may be enhanced by ferrimagnetic and antiferromagnetic materials. Furthermore, we will present our recent findings on strengths and limitations of skyrmionic applications and the predictability of their performances.