Multi-scale analysis of strain-dependent magnetocrystalline anisotropy and strain-induced Villari and Nagaoka-Honda effects in a two-dimensional ferromagnetic chromium tri-iodide monolayer

Abstract

This paper analyzes the magnetic properties of the emerging ferromagnetic chromium tri-iodide (CrI3) monolayer, under compressive and tensile biaxial strains. By combining first-principles density functional theory and Metropolis Monte Carlo methods, the multi-scale simulations are used to quantitatively analyze the strain-dependent magnetocrystalline anisotropy energy, Heisenberg isotropic symmetric exchange effects, anisotropic symmetric exchange effects, magnetic moment, and Curie temperature (Tc). The Villari effect (or the inverse magnetostrictive effect) and the Nagaoka-Honda effect (or the inverse Barret effect) are unraveled. It is shown that a small strain (e.g., smaller than 1%) could change Tc by only less than 1 K. By contrast, a small strain can noticeably influence the hysteresis curve shape and significantly alter the coercive magnetic field (Bc), which offers one of the possible explanations of the large variation of Bc as measured on the strain-prone exfoliated CrI3 monolayers. This also indicates the importance to vanish strain to ensure small device-to-device variation of magnetic properties in the monolayer-based spintronics memory and logic devices. It is revealed that strain can induce changes on a series of key magnetic properties (e.g., the strain-induced magnetization direction flip, the strain-induced ferromagnetic/antiferromagnetic transition, the strain-induced change of magnetic coercivity, etc.), which might be useful to enable monolayer-based sensor applications.