Query: Scalable energy-efficient magnetoelectric spin–orbit logic.

Candidate papers:

abstract: Since the early 1980s, most electronics have relied on the use of complementary metal oxide semiconductor (CMOS) transistors. However, the principles of CMOS operation, involving a switchable semiconductor conductance controlled by an insulating gate, have remained largely unchanged, even as transistors are miniaturized to sizes of 10 nanometres. We investigated what dimensionally scalable logic technology beyond CMOS could provide improvements in efficiency and performance for von Neumann architectures and enable growth in emerging computing such as artifical intelligence. Such a computing technology needs to allow progressive miniaturization, reduce switching energy, improve device interconnection and provide a complete logic and memory family. Here we propose a scalable spintronic logic device that operates via spin orbit transduction (the coupling of an electron's angular momentum with its linear momentum) combined with magnetoelectric switching. The device uses advanced quantum materials, especially correlated oxides and topological states of matter, for collective switching and detection. We describe progress in magnetoelectric switching and spin orbit detection of state, and show that in comparison with CMOS technology our device has superior switching energy (by a factor of 10 to 30) lower switching voltage (by a factor of 5) and enhanced logic density (by a factor of 5) In addition, its non volatility enables ultralow standby power, which is critical to modern computing. The properties of our device indicate that the proposed technology could enable the development of multi generational computing.A scalable spintronic device operating via spin orbit transduction and magnetoelectric switching and using advanced quantum materials shows non volatility and improved performance and energy efficiency compared with CMOS devices.
author_names: Sasikanth Manipatruni

Dmitri E Nikonov

Chia-Ching Lin

Tanay A Gosavi

Huichu Liu

Bhagwati Prasad

Yen-Lin Huang

E Bonturim

Ramamoorthy Ramesh

Ian A Young
title: Scalable energy efficient magnetoelectric spin orbit logic
venue: Nature
year: 2018

abstract: As nanoelectronics approaches the nanometer scale 1 4 a massive effort is underway to identify an energy efficient scalable logic technology beyond Complementary Metal Oxide Semiconductor (CMOS) transistor based computing 5 7 Such computing technology needs to improve switching energy and delay at reduced dimensions 8 allow improved interconnects 9 and provide a complete logic/memory family. However, a viable beyond CMOS logic technology has remained elusive. Here, we propose a scalable spintronic logic device which operates via spin orbit transduction 10 16 combined with magneto electric switching 17 20 The MagnetoElectric Spin Orbit (MESO) logic enables a new paradigm to continue scaling of logic 8,9,21 to switching energies of <10aJ per device at switching delay of 100 ps.
author_names: Ian A Young

Sasikanth Manipatruni

Dmitri E Nikonov

C -C Lin

Huquan Li

Ramamoorthy Ramesh
title: Magneto Electric Spin Orbit Logic and Spin Orbit Memory Building Blocks for Beyond CMOS
year: 2017

abstract: In this technical note, we address the comments on the energy estimates for Magnetoelectric Spin orbit (MESO) Logic, a new logic device proposed by the authors. We provide an analytical derivation of the switching energy, and support it with time domain circuit simulations using a self consistent ferroelectric (FE) compact model. While the energy to charge a capacitor is dissipated in the interconnect and transistor resistance, we note that the energy to switch a capacitor and a FE is independent of the interconnect resistance value to the first order. Also device design can mitigate the parasitic energy losses. We further show the circuit simulations for a sub 10 aJ switching operation of a MESO logic device comprehending: a) Energy stored in multiferroic; b) Energy dissipation in the resistance of the interconnect, Ric c) Energy dissipation in the inverse spin orbit coupling (ISOC) spin to charge converter Risoc; d) Supply, ground resistance, and transistor losses. We also identify the requirements for the resistivity of the spin orbit coupling materials and address the effect of internal resistance of the spin to charge conversion layer. We provide the material parameter space where MESO (with a fan out of 1 and interconnect) achieves sub 10 aJ switching energy with path for scaling via ferroelectric/magnetoelectric/spin orbit materials development.
author_names: Sasikanth Manipatruni

Dmitri E Nikonov

Huichu Liu

Ian A Young
title: Response to Comment on 'Spin Orbit Logic with Magnetoelectric Nodes: A Scalable Charge Mediated Nonvolatile Spintronic Logic' (arXiv:1607.06690)
year: 2017

abstract: As nanoelectronics approaches the nanometer scale, a massive effort is underway to identify the next scalable logic technology beyond Complementary Metal Oxide Semiconductor (CMOS) computing. Such computing technology needs to improve switching energy delay at reduced dimensions, allow improved interconnects and provide a complete logic/memory family. However, a viable beyond CMOS logic technology has remained elusive. Here, we propose a scalable spintronic logic device which operates via spin orbit transduction combined with magneto electric switching. The proposed Magneto Electric Spin Orbit (MESO) logic enables a new paradigm to continue scaling of logic performance to near thermodynamic limits for GHz logic (100 kT switching energy at 100 ps delay) The proposed MESO devices scale strongly and favorably with critical dimensions of the device, showing a cubic dependence of switching energy on size, (E_m proportional to W^3) and square dependence on voltage (E_m proportional to V^2) The excellent scaling is obtained thanks to the properties of the spin orbit effects (e.g. Inverse Spin Hall Effect (ISHE) and Inverse Rashba Edelstein Effect (IREE) and the dependence of capacitance on size. The operating voltages for these devices are predicted to be 100 mV allowing a significant jump ahead of historic trends of scaling voltage with size and corresponding reduction of energy. Interconnect resistance is a critical obstacle for scaling beyond 10 nm dimensions. We project a less detrimental impact of interconnect resistance and show that MESO logic is amenable for highly resistive interconnects (100 uOhm.cm 1 mOhm.cm) which opens a possibility to use nano metallic (width bulk electron mean free path) or doped semiconducting wires (width<5 nm) A scalable, CMOS compatible, non volatile logic family proposed here may enable the next multi generational scaling of computing devices.
author_names: Sasikanth Manipatruni

Dmitri E Nikonov

Ramamoorthy Ramesh

Huichu Li

Ian A Young
title: Spin Orbit Logic with Magnetoelectric Nodes: A Scalable Charge Mediated Nonvolatile Spintronic Logic
year: 2015

abstract: Researchers from Intel Corporation recently proposed "Magneto Electric Spin Orbit (MESO)" logic as a new strategy for beyond CMOS electronics [1] The Intel researchers project that this concept has the potential to reduce the switching energy per bit "to near thermodynamic limits for GHz logic (100 kT switching at 100 ps delay)" i.e. to near 0.4 aJ. Here I point out that the switching energy stated in ref. [1] is incorrect, because the paper neglects a large energy cost associated with Ohmic dissipation that is unavoidable within the MESO scheme. Using optimistic parameters, the true minimum switching energy per bit within the MESO approach is at least 150 fJ, or more than 300,000 times greater than the value stated in ref. [1] Given this large energy cost, the MESO concept is not a viable strategy for beyond CMOS logic.
author_names: Daniel C Ralph
title: Comment on "Spin Orbit Logic with Magnetoelectric Nodes: A Scalable Charge Mediated Nonvolatile Spintronic Logic" (arXiv:1512.05428)
year: 2016

abstract: The supply voltage scaling has become increasingly challenging in the advanced CMOS technology due to the threshold voltage requirement for transistor OFF leakage, limiting the system energy efficiency. Spintronic logic utilizes the physical quantity of magnetization or spin as a computation variable, offering new design paradigms in terms of ultralow voltage operation and nonvolatility, but suffering from switching inefficiency of the charge to spin conversion. The magnetoelectric spin orbit (MESO) device has been proposed as a new alternative logic device candidate to solve these issues by magnetoelectric transduction using a novel multiferroic oxide [both ferroelectric (FE) and antiferromagnetic] a ferromagnet and a spin injection layer. It enables a path toward 10 100 \times switching energy reduction compared to CMOS inverter in 2018 node, due to the device and material innovations of a novel switching mechanism. In this paper, in order to build a MESO logic family for new circuit and architecture exploration, we propose for the first time the fundamental building blocks such as MESO sequential and combinatorial circuits for the synchronous logic operation. We employ a transistor sharing and a novel multiphase clocking scheme to address the circuit design issues such as clock control, directionality of state propagation, and power gating and enable the design exploration for MESO digital logic. Based on the proposed circuit techniques, we demonstrate these MESO logic functions operating at a supply voltage of 100 mV and a clock period of 1.2 ns with 320 ac FE polarization through the circuit simulations.
author_names: Huichu Liu

Sasikanth Manipatruni

Daniel H Morris

Kaushik Vaidyanathan

Dmitri E Nikonov

Tanay Karnik

Ian A Young
title: Synchronous Circuit Design With Beyond CMOS Magnetoelectric Spin Orbit Devices Toward 100 mV Logic
venue: IEEE Journal on Exploratory Solid State Computational Devices and Circuits
year: 2019

abstract: As electronic integrated circuits are scaled to ever smaller sizes, they run into the obstacle of excessive power dissipation. Spintronic devices hold the promise of alleviating this problem via improved energy efficiency. Research effort around a promising class of such devices based on antiferromagnetic materials and magnetoelectric switching is reviewed.
author_names: Peter A Dowben

D E Nikonov

A Marshall

Christian Binek
title: Magneto electric antiferromagnetic spin orbit logic devices
year: 2020

abstract: The spin degree of freedom in magnetic devices has been discussed widely for computing, since it could significantly reduce energy dissipation, might enable beyond Von Neumann computing, and could have applications in quantum computing. For spin based computing to become widespread, however, energy efficient logic gates comprising as few devices as possible are required. Considerable recent progress has been reported in this area. However, proposals for spin based logic either require ancillary charge based devices and circuits in each individual gate or adopt principals underlying charge based computing by employing ancillary spin based devices, which largely negates possible advantages. Here, we show that spin orbit materials possess an intrinsic basis for the execution of logic operations. We present a spin orbit logic gate that performs a universal logic operation utilizing the minimum possible number of devices, that is, the essential devices required for representing the logic operands. Also, whereas the previous proposals for spin based logic require extra devices in each individual gate to provide reconfigurability, the proposed gate is 'electrically' reconfigurable at run time simply by setting the amplitude of the clock pulse applied to the gate. We demonstrate, analytically and numerically with experimentally benchmarked models, that the gate performs logic operations and simultaneously stores the result, realizing the 'stateful' spin based logic scalable to ultralow energy dissipation.
author_names: Mohammad Kazemi
title: An electrically reconfigurable logic gate intrinsically enabled by spin orbit materials
venue: Scientific Reports
year: 2017

abstract: As we approach the limits of CMOS scaling, researchers are developing "beyond CMOS" technologies to sustain the technological benefits associated with device scaling. Spin tronic technologies have emerged as a promising beyond CMOS technology due to their inherent benefits over CMOS such as high integration density, low leakage power, radiation hardness, and non volatility. These benefits make spintronic devices an attractive successor to CMOS especially for memory circuits. However, spintronic devices generally suffer from slower switching speeds and higher write energy, which limits their usability. In an effort to close the energy delay gap between CMOS and spintronics, device concepts such as CoMET (Composite Input Magnetoelectric base Logic Technology) have been introduced, which collectively leverage material phenomena such as the spin Hall effect and the magnetoelectric effect to enable fast, energy efficient device operation. In this work, we propose a non volatile flip flop (NVFF) based on CoMET technology that is capable of achieving up to two orders of magnitude less write energy than CMOS. This low write energy (2 aJ) makes our CoMET NVFF especially attractive to architectures that require frequent backup operations e.g. for energy harvesting non volatile processors.
author_names: Robert Perricone

Zhaoxin Liang

Meghna G Mankalale

Michael Thaddeus Niemier

Sachin S Sapatnekar

Jianping Wang

Xiaobo Sharon Hu
title: An Energy Efficient Non Volatile Flip Flop based on CoMET Technology
venue: 2019 Design, Automation Test in Europe Conference Exhibition (DATE)
year: 2019

abstract: Reliable and energy efficient magnetization switching by electrically induced spin orbit torques is of crucial technological relevance for spintronic devices implementing memory and logic functionality. Here we predict that the strength of spin orbit torques and the Dzyaloshinskii Moriya interaction in topologically nontrivial magnetic insulators can exceed by far that of conventional metals. In analogy to the quantum anomalous Hall effect, we explain this extraordinary response in the absence of longitudinal currents as hallmark of monopoles in the electronic structure of systems that are interpreted most naturally within the framework of mixed Weyl semimetals. We thereby launch the effect of spin orbit torque into the field of topology and reveal its crucial role in mediating the topological phase transitions arising from the complex interplay between magnetization direction and momentum space topology. The presented concepts may be exploited to understand and utilize magnetoelectric coupling phenomena in insulating ferromagnets and antiferromagnets.Electric field control of magnetization switching is highly promising for low dissipation spintronics. Here, the authors propose an electrically induced topological phase transition mediated by spin orbit torques as attractive way to control magnetization in absence of longitudinal charge currents.
author_names: Jan-Philipp Hanke

Frank Freimuth

Chengwang Niu

Stefan Blugel

Yuriy Mokrousov
title: Mixed Weyl semimetals and low dissipation magnetization control in insulators by spin orbit torques
venue: Nature Communications
year: 2017