Very large Dzyaloshinskii-Moriya interaction in two-dimensional Janus manganese dichalcogenides and its application to realize skyrmion states

TL;DR

This paper demonstrates significant Dzyaloshinskii-Moriya interactions in Janus manganese dichalcogenide monolayers, enabling the formation of skyrmion states at low temperatures, which could lead to novel 2D magnetic devices.

Contribution

First-principles calculations reveal large DMI in Janus MnXY monolayers, enabling skyrmion states and expanding 2D magnetic material functionalities.

Findings

DMI amplitudes in MnSeTe and MnSTe are comparable to advanced heterostructures.

Skyrmion states can be stabilized in these monolayers under magnetic fields.

Skyrmion states fluctuate above 50 K, indicating potential for room-temperature applications.

Abstract

The Dzyaloshinskii-Moriya interaction (DMI), which only exists in noncentrosymmetric systems, is responsible for the formation of exotic chiral magnetic states. The absence of DMI in most two-dimensional (2D) magnetic materials is due to their intrinsic inversion symmetry. Here, using first-principles calculations, we demonstrate that significant DMI can be obtained in a series of Janus monolayers of manganese dichalcogenides MnXY in which the difference between X and Y on the opposites sides of Mn breaks the inversion symmetry. In particular, the DMI amplitudes of MnSeTe and MnSTe are comparable to those of state-of-the-art ferromagnet/heavy metal (FM/HM) heterostructures. In addition, by performing Monte Carlo simulations, we find that at low temperatures the ground states of the MnSeTe and MnSTe monolayers can transform from ferromagnetic states with worm-like magnetic domains into the skyrmion states by applying external magnetic field. At increasing temperature, the skyrmion states starts fluctuating above 50 K before an evolution to a completely disordered structure at higher temperature. The present results pave the way for new device concepts utilizing chiral magnetic structures in specially designed 2D ferromagnetic materials.