Theoretical investigation of MnFe2O4

Abstract

Generalized gradient approximation (GGA) and GGA + U (U is the Hubbard parameter) were applied to scrutinize the electronic structure and magnetic properties of the spinel ferrite MnFe2O4. Compression between GGA and GGA + U calculations were carried out. Oxygen position (z), total unit crystal spin magnetic moment, and lattice parameters were optimized. The optimized structure parameters are in good agreement with the experimental values. The experimental results described by the GGA + U calculations are better than the normal frame work. A new method for calculating U has been introduced. The calculations show that Mn ferrite has cubic structure with ordered spins. The compound should experience insulating behaviors which is experimentally observed. Such insulating behavior and spin ordering increase the ability of using Mn ferrite in high frequency applications. The moments are predominantly due to the ionic model behaviors for this compound. High spin state is favorable for the two cations Mn and Fe. From the anomalous explanation of DOS it is observed that, a ferrimagnetic spin current between Fe-3d and Mn-3d through O-2p is yielded. The flat bands, which are the more atomic-like lead to a high density of states and magnetic instability of local moment character. The effect of decreasing octahedral point group from Oh to D4h, C4v and C3v were carried out. The octahedral deformation has not been found in Mn ferrite. Total picture study for Hubbard parameter U has been carried out where accurate value for U was determined by comparing the energy gap with that obtained experimentally. Correlated behavior was proved for Manganese ferrite.