Low Power In-Memory Computation with Reciprocal Ferromagnet/Topological Insulator Heterostructures

Hamed Vakili; Samiran Ganguly; George J de Coster; Mahesh R Neupane; Avik W Ghosh

doi:10.1021/acsnano.2c05645

Low Power In-Memory Computation with Reciprocal Ferromagnet/Topological Insulator Heterostructures

ACS Nano. 2022 Dec 27;16(12):20222-20228. doi: 10.1021/acsnano.2c05645. Epub 2022 Dec 2.

Authors

Hamed Vakili¹, Samiran Ganguly^{2

3}, George J de Coster⁴, Mahesh R Neupane^{4

5}, Avik W Ghosh^{1

2}

Affiliations

¹ Department of Physics, University of Virginia, Charlottesville, Virginia22904, United States.
² Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, Virginia22904, United States.
³ Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia23284, United States.
⁴ DEVCOM Army Research Laboratory, 2800 Powder Mill Road, Adelphi, Maryland20783, United States.
⁵ Materials Science and Engineering Program, University of California, Riverside, California92521, United States.

Abstract

The surface state of a 3D topological insulator (3DTI) is a spin-momentum locked conductive state, whose large spin hall angle can be used for the energy-efficient spin-orbit torque based switching of an overlying ferromagnet (FM). Conversely, the gated switching of the magnetization of a separate FM in or out of the TI surface plane can turn on and off the TI surface current. By exploiting this reciprocal behavior, we can use two FM/3DTI heterostructures to design an integrated 1-transistor 1-magnetic tunnel junction random access memory unit (1T1MTJ RAM) for an ultra low power Processing-in-Memory (PiM) architecture. Our calculation involves combining the Fokker-Planck equation with the Nonequilibrium Green Function (NEGF) based flow of conduction electrons and Landau-Lifshitz-Gilbert (LLG) based dynamics of magnetization. Our combined approach allows us to connect device performance metrics with underlying material parameters, which can guide proposed experimental and fabrication efforts.

Keywords: 3D topological insulator; ferromagnetic heterostructures; in-memory computing; quantum transport; spintronics.