Pressure induced isostructural phase transition in biskyrmion host hexagonal MnNiGa

TL;DR

This study reports an isostructural phase transition in hexagonal MnNiGa at around 4 GPa, revealing pressure-induced changes in crystal structure while maintaining hexagonal symmetry, and highlighting magnetoelastic effects on skyrmion textures.

Contribution

It provides the first observation of an isostructural phase transition in MnNiGa under pressure, with detailed analysis of anisotropic compression and its implications for skyrmion manipulation.

Findings

Isostructural phase transition at ~4 GPa

Anisotropic compression behavior observed

Hexagonal symmetry remains stable up to 14 GPa

Abstract

Magnetic skyrmions are vortex-like spin textures, which can be manipulated by external stress or pressure via magnetoelastic effects. Here, we present the observation of isostructural phase transition in a biskyrmion host hexagonal MnNiGa at a pressure around 4 GPa using pressure-dependent synchrotron x-ray powder diffraction (XRD) data analysis. Our XRD data reveals anisotropic compression behavior with pressure with different compression rates of the a-axis in the basal plane and the c-axis in the prismatic plane. However, the hexagonal symmetry remains unchanged for pressure up to 14 GPa. Fitting of unit cell volume with pressure using a second-order Birch-Murnagan equation of state reveals that the data to fall into two distinct curves for those above and below 4 GPa. The present study contributes to the understanding of crystal structure with the application of hydrostatic pressure in the biskyrmion host MnNiGa, wherein the skyrmion textures can be manipulated by pressure due to their magnetoelastic character.