Structural phase transitions in VSe2: energetics, electronic structure and magnetism

TL;DR

This study uses first principles calculations to explore the energetics, electronic structure, and magnetism of VSe2 during structural phase transitions, revealing low energy barriers and the influence of strain and magnetic states.

Contribution

It provides detailed insights into the energetics and magnetic properties of VSe2 phases, highlighting the role of strain and atomic motions in phase stability.

Findings

Low energy barrier (0.60 eV) for phase transition in monolayer VSe2.

Ferromagnetic configuration is the ground state across stable structures.

Strain effects suggest the T phase is stabilized by substrate-induced strain.

Abstract

First principles calculations of magnetic and electronic properties of VSe2 describing the transition between two structural phases(H,T) were performed. Results of the calculations evidence rather low energy barrier ( 0.60 eV for monolayer) for transition betweenthe phases. The energy required for the deviation of Se atom or whole layer of selenium atoms on a small angle up to 10 degrees from initial positions is also rather low, 0.32 and 0.19 eV/Se, respectively. The changes in band structure of VSe2 caused by these motions of Se atoms should be taken into account for analysis of the experimental data. Simulations of the strain effects suggest that the experimentally observed T phase of VSe2 monolayer is the ground state due a substrate-induced strain. Calculations of the difference in total energies of ferromagnetic and antiferromagnetic configurations evidence that the ferromagnetic configuration is the ground state of the system for all stable and intermediate atomic structures. Calculated phonon dispersions suggest visible influence of magnetic configurations on vibrational properties.