Design rules for scalability in spin-orbit electronics

Mohammad Kazemi,Mark F Bocko

doi:10.1038/s41598-019-49831-5

Abstract

Spin-orbit electronics (spin-orbitronics) has been widely discussed for enabling nonvolatile devices that store and process information with low power consumption. The potential of spin-orbitronics for memory and logic applications has been demonstrated by perpendicular anisotropy magnetic devices comprised of heavy-metal/ferromagnet or topological-insulator/ferromagnet bilayers, where the heavy metal or topological insulator provides an efficient source of spin current for manipulating information encoded in the bistable magnetization state of the ferromagnet. However, to reliably switch at room temperature, spin-orbit devices should be large to reduce thermal fluctuations, thereby compromising scalability, which in turn drastically increases power dissipation and degrades performance. Here, we show that the scalability is not a fundamental limitation in spin-orbitronics, and by investigating the interactions between the geometry of the ferromagnetic layer and components of the spin-orbit torque, we derive design rules that lead to deeply scalable spin-orbit devices. Furthermore, employing experimentally verified models, we propose deeply scaled spin-orbit devices exhibiting high-speed deterministic switching at room temperature. The proposed design principles are essential for design and implementation of very-large-scale-integration (VLSI) systems that provide high performance operation with low power consumption.

Highlights

Spin-orbit electronics has been widely discussed for enabling nonvolatile devices that store and process information with low power consumption
We further show that the design rules enable high speed switching operation with low power consumption, suggesting the spin-orbitronics as a promising candidate for post-CMOS systems delivering high performance operation with low power consumption
We show that scalability is not a fundamental limitation in spin-orbitronics and provide design rules for achieving deeply scalable spin-orbit devices with high speed switching at room temperature

Summary

Introduction

Spin-orbit electronics (spin-orbitronics) has been widely discussed for enabling nonvolatile devices that store and process information with low power consumption. To reliably switch at room temperature, spin-orbit devices should be large to reduce thermal fluctuations, thereby compromising scalability, which in turn drastically increases power dissipation and degrades performance. The advent of spin-orbit magnetic heterostructures[3], such as heavy-metal/ferromagnet[4,5,6,7,8,9,10] and topological-insulator/ferromagnet[11,12,13,14,15] thin films, renders magnetic devices promising for the implementation of power efficient memory, logic, and machine learning systems. As the volume of the ferromagnet is reduced by scaling the device dimensions, to ensure nonvolatility, the antisymmetric exchange interactions[16,17,18] should be suppressed and the anisotropy energy density should be increased. The PMA is not limited by the planar geometry of the device and may extend to relatively large values required for nonvolatility at smaller dimensions

Methods

Findings

Discussion

Conclusion