Strain induced incommensurate phases in hexagonal manganites

TL;DR

This study uses theoretical models to explore how in-plane strain influences incommensurate phases and domain structures in hexagonal manganites, revealing temperature and strain effects on phase stability and vortex dynamics.

Contribution

It introduces a combined Landau and phase-field approach to analyze strain-induced incommensurate phases in hexagonal manganites, providing new insights into their phase diagram and vortex behavior.

Findings

Equilibrium wavelength depends on temperature and strain magnitude.

Strain influences vortex and antivortex dynamics, including creation and annihilation.

A temperature-strain phase diagram for incommensurate phase stability is constructed.

Abstract

An incommensurate phase refers to a solid state in which the period of a superstructure is incommensurable with the primitive unit cell. Recently the incommensurate phase is induced by applying an in-plane strain to hexagonal manganites, which demonstrates single chiral modulation of six domain variants. Here we employ Landau theory in combination with the phase-field method to investigate the incommensurate phase in hexagonal manganites. It is shown that the equilibrium wave length of the incommensurate phase is determined by temperature and the magnitude of the applied strain, and a temperature-strain phase diagram is constructed for the stability of the incommensurate phase. Temporal evolution of domain structures reveals that the applied strain not only produces the force pulling the vortices and anti-vortices in opposite directions, but also results in the creation and annihilation of vortex-antivortex pairs.