Probing magnetoelastic coupling and structural changes in magnetoelectric gallium ferrite

摘要

Temperature dependent x-ray diffraction and Raman spectroscopic studies were carried out on flux-grown single crystals of gallium ferrite with a Ga:Fe ratio of 0.9:1.1. Site occupancy calculations from the Rietveld refinement of the x-ray data led to an estimated magnetic moment of 0.60μ_B/f.u. which was in good agreement with the experimental data. A combination of these two measurements indicates that there is no structural phase transition in the material between 18 and 700K. A detailed line shape analysis of the Raman mode at ～374cm~(-1) revealed a discontinuity in the peak position data indicating the presence of spinphonon coupling in gallium ferrite. A correlation of the peak frequency with the magnetization data led to two distinct regions across a temperature ～180K with appreciable change in the spinphonon coupling strength from ～0.9(T<180K) to 0.12cm~(-1) (180K