Spin dynamics and Phonons of the Chromites CoCr2O4 and MnCr2O4

Abstract Due to the geometric magnetic frustration inherent to their lattice and the resulting complex magnetic states, the spinel compounds are of great interest in both fundamental and application-oriented perspectives. Here, we applied x-ray diffraction, magnetization, heat capacity and powder inelastic neutron scattering measurements, along with theoretical calculations, to study the exotic properties of chromite-spinel oxides, CoCr 2 O 4 and MnCr 2 O 4 . The temperature dependence of the phonon spectra provides an insight into the correlation between oxygen motion and the magnetic order, as well as the magnetoelectric effect in the ground state of MnCr 2 O 4 . Moreover, spinwave excitations in CoCr 2 O 4 and MnCr 2 O 4 are compared with Heisenberg model calculations. This approach enables the precise determination of exchange energies and offers a comprehensive understanding of the spin dynamics and relevant exchange interactions in complicated spiral spin ordering.