Skyrmion host GaV₄S₈ under high pressure

Recently, GaV₄S₈, received global attention due to the whirl-like topological spins rotating along the radial direction discovered in this material. Previous investigations indicate the important role of the structure behind the multiferroicity. For example, the crystal structure transition coupling with a magnetic ordering at ~40 K. In the present work, we use compression to alter the structure and thus changing material’s properties to establish the interrelation between the structural, optical, and electrical properties for our better understanding this skyrmion host material. Upon this objective, in-situ high-pressure measurements of single crystal/powder X-ray diffraction, electrical conductivity, and Raman were carried out by using a diamond anvil cell. These multi-characterizations found and verified the structural transformation from cubic to orthorhombic along with a transition from semi-conductor to metallic material in GaM₄X₈. We also determined the bulk modulus of the two phases of GaM₄X₈ by fitting the data set of unit cell volumes against pressure with the second-order birth-Murnaghan equation of state, and attempted to explain the mechanisms of phase transitions by means of Jahn-teller effect and the anisotropic changes in bonding lengths during compression.