Atomistic modeling of spin and electron dynamics in two-dimensional magnets switched by two-dimensional topological insulators

TL;DR

This paper models the spin and electron dynamics in heterostructures of 2D magnets and topological insulators, proposing a pathway for fast, efficient magnetic switching in memory devices through interface engineering.

Contribution

It introduces a theoretical framework combining Green's functions and Monte Carlo simulations to analyze spin-charge interactions in 2D heterostructures for memory applications.

Findings

Magnetic domains can be switched via spin-torque from 2D topological insulators.

Switching efficiency depends critically on interface exchange interaction.

Higher anisotropy materials offer more stable magnetic order but slower switching.

Abstract

To design fast memory devices, we need material combinations which can facilitate fast read and write operation. We present a heterostructure comprising a two-dimensional (2D) magnet and a 2D topological insulator (TI) as a viable option for designing fast memory devices. We theoretically model spin-charge dynamics between the 2D magnets and 2D TIs. Using the adiabatic approximation, we combine the non-equilibrium Green's function method for spin-dependent electron transport, and time-quantified Monte-Carlo for simulating magnetization dynamics. We show that it is possible to switch the magnetic domain of a ferromagnet using spin-torque from spin-polarized edge states of 2D TI. We further show that the switching between TIs and 2D magnets is strongly dependent on the interface exchange ($J_{\mathrm{int}}$), and an optimal interface exchange depending on the exchange interaction within the magnet is required for efficient switching. Finally, we compare the experimentally grown Cr-compounds and show that Cr-compounds with higher anisotropy (such as $\rm CrI_3$) results in lower switching speed but more stable magnetic order.