Pressure and field tuning the magnetostructural phases of Mn3O4: Raman scattering and x-ray diffraction studies

We present temperature-, magnetic-field-, and pressure-dependent Raman scattering studies of single crystal Mn3O4, combined with temperature-and field-dependent x-ray diffraction studies, revealing the novel magnetostructural phases in Mn3O4. Our temperature-dependent studies show that the commensurate magnetic transition at T-2 = 33 K in the binary spinel Mn3O4 is associated with a structural transition from tetragonal to orthorhombic structures. Field-dependent studies show that the onset and nature of this structural transition can be controlled with an applied magnetic field, and reveal evidence for a field-tuned quantum phase transition to a tetragonal spin-disordered phase for H parallel to[110]. Pressure-dependent Raman measurements indicate that the magnetic easy-axis direction in Mn3O4 can be controlled-and the ferrimagnetic transition temperature increased-with applied pressure. Finally, combined pressure-and magnetic-field-tuned Raman measurements reveal a rich magnetostructural phase diagram-including a pressure-and field-induced magnetically frustrated tetragonal phase in the P-H (pressure-magnetic field) phase diagram-that can be generated in Mn3O4 with applied pressure and magnetic field.