Structural and magnetic transitions in spinel FeMn2O4 single crystals

Abstract

Materials that form the spinel structure are known to exhibit geometric frustration, which can lead to magnetic frustration as well. Through magnetization and neutron diffraction measurements, we find that FeMn2O4 undergoes one structural and two magnetic transitions. The structural transition occurs at Ts∼595K from cubic at high temperatures to tetragonal at low temperatures. Two magnetic transitions are ferrimagnetic at TFI−1∼373K and TFI−2∼50K, respectively. Further investigation of the specific heat, thermal conductivity, and Seebeck coefficient confirms both magnetic transitions. Of particular interest is that there is a significant magnetic contribution to the low-temperature specific heat and thermal conductivity, providing a unique system to study heat transport by magnetic excitations.