Mapping the magnetostructural quantum phases of Mn3O4.

We present temperature-dependent x-ray diffraction and temperature- and field-dependent Raman scattering studies of single-crystal Mn3O4, which reveal the magnetostructural phases that evolve in the spinels due to the interplay between strong spin-orbital coupling, geometric frustration, and applied magnetic field. We present evidence that the magnetoelastic and magnetodielectric behavior in this material is governed by magnetic-field-controlled tetragonal-to-monoclinic phase changes. Most interestingly, for an applied field transverse to the ferrimagnetic ordering direction, H parallel [110], we find evidence for a field-tuned quantum phase transition to a tetragonal spin-disordered phase, indicating that a structurally symmetric, spin frustrated phase can be recovered at T approximately 0 for intermediate transverse fields in Mn3O4.