Pressure-driven structural and electronic phase transitions in type II multiferroic MnSb2Se4

AB2X4 (where A = Fe, Mn; B = Sb, Bi; and X = S, Se, Te) family of materials has attracted researchers after the observation of Quantum Anomalous Hall Effect in MnBi2Te4 [1][2][3].Recent studies on MnSb2Se4 based on first-principle calculations predicted that it could be converted into Weyl semimetal at a pressure ~ 0.85 GPa and to a 3D anti-ferromagnetic topological insulator at ~ 2.45 GPa [4].We report high pressure Raman Spectroscopy and synchrotron X-ray diffraction studies on polycrystalline MnSb2Se4 till 12 GPa exploring the topological, electronic and structural phase transitions.The material crystallises in C2/m monoclinic phase and under pressure it shows some intriguing behaviour, with some Raman modes softening and some others hardening which indicates strong anisotropy in the system.Pressure evolution of Raman modes and their full width at half maximum show slope changes at ~0.5 GPa and ~2.0 GPa.The XRD results show changes at ~1.9 GPa and at ~5 GPa with the coexistence of phases and the structure is reversible with pressure release.