Room-temperature ground magnetic state of ε-Fe2O3: In-field Mossbauer spectroscopy evidence for collinear ferrimagnet

epsilon-Fe2O3 is a remarkable iron(III) oxide polymorph exhibiting a large room-temperature (RT) coercive field, coupled magnetoelectric properties, and millimeter-wave ferromagnetic resonance. Despite great application potential, its room-temperature ground magnetic state is still under scrutiny. Employing in-field Fe-57 Mossbauer spectroscopy, we unambiguously demonstrate that at room temperature, epsilon-Fe2O3 behaves as a collinear ferrimagnet, hence excluding any canting of sublattice magnetizations. When exposed to an external magnetic field, epsilon-Fe2O3 can be modeled as a two-sublattice ferrimagnetic nanomaterial with the highest coercivity among all currently known ferrimagnetic (nano) materials. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3671114]