Intrinsic multiferroic semiconductors with magnetoelastic coupling: two-dimensional MoTe<i>X</i> (<i>X</i> = F, Cl, Br, I) monolayers

Abstract

Two-dimensional materials with both ferromagnetism and ferroelasticity present new possibilities for developing spintronics and multifunctional devices. These materials provide a novel method for controlling the direction of the magnetization axis by switching the ferroelastic state, achieving efficient and low-power operation of magnetic devices. Such properties make them a promising candidate for the next generation of non-volatile memory, sensors, and logic devices. By performing the first-principles calculations, the ferromagnetism, ferroelasticity, and magnetoelastic coupling in MoTe<i>X</i> (<i>X</i>=F, Cl, Br, I) monolayers are systematically investigated. The results indicate that the MoTe<i>X</i> monolayers are intrinsic semiconductors holding both ferromagnetism and ferroelasticity. The pronounced in-plane magnetic anisotropy suggests that the MoTe<i>X</i> monolayers can resist thermal disturbances and maintain long-range magnetic order. The Curie temperatures of MoTe<i>X</i> monolayers are 144.75 K, 194.55 K, 111.45 K, and 92.02 K, respectively. Our calculations show that the four MoTe<i>X</i> monolayers possess two stable ferroelastic states, with their easy magnetization axes perpendicular to each other. The ferroelastic transition barriers between the two ferroelastic states of MoTeF, MoTeCl, MoTeBr, MoTeI monolayers are 0.180 eV/atom, 0.200 eV/atom, 0.209 eV/atom, and 0.226 eV/atom, respectively, with their corresponding reversible strains of 54.58%, 46.32%, 43.06%, and 38.12%. These values indicate the potential for reversible magnetic control through reversible ferroelastic transition at room temperature. Owing to their unique magnetoelastic coupling properties, MoTe<i>X</i> monolayers exhibit the ability to control reversible magnetization axis at room temperature, laying the foundation for the development of highly controllable and stable spintronic devices.