Ab-initio study and atomistic spin model simulations of Cr2O3 thin films

Abstract

Magnetoelectric random access memory (MERAM) is the next generation technology of data storage with high-density and low power. Magnetoelectric material can be controlled by voltage such as an electric field to transform spin domain directions for storing data. One of the most promising materials that possess such properties near room temperature is Cr2O3. Although, the bulk has perfect properties for MERAM, it is necessary to fabricate thin films for applicable spintronic devices, i.e., reducing the required external control voltage; however, the film magnetic and physical properties might be different from bulk. In this work, we propose that the film properties might be induced by surface effects and are confirmed with Ab-initio calculation and atomistic spin simulation. The main simulation processes are the density functional theory (DFT) calculating, mapped with the classical Heisenberg model for exchange interaction constants up to the fifth nearest neighbour (J 1-J 5). The atomistic spin model was then used to approximate the Néel temperature (T N), comparing two methods i.e., Monte Carlo simulation and the Landau–Lifshitz–Gilbert (LLG) equation. The Néel temperatures of the film were found to be slightly lower than the bulk, which is in good agreement with previous experiments. Furthermore, the spin dynamic model gives more correct result comparing to the Monte Carlo method.