Magnetic Properties of Synthetic Single Crystal of αFe2O3

Abstract

Synthetic single crystals were grown by the flux method. It was confirmed that the weak ferromagnetic moment appears only when the spins lie in the (111) plane. Contrary to the case of polycrystallines specimens, recovery of the residual magnetization or the memory phenomenon is not observed. It was found, below the transition temperature, a very small amount of the residual magnetic moment along the direction of the field during cooling. Microwave (36,000 MC/sec) resonance studies found a very small six-fold anisotropy ( K h =0.09 erg/gr.) in the (111) plane. The resonance line was easily broadened by stresses applied on the crystals. A reasonable agreement is obtained with the data of microwave studies by Abe et al., after taking into account the effect of magnetoelastic coupling. It is suggested that internal strains may induce a dominant uniaxial anisotropy in the (111) plane in polycrystals through their magnetoelastic coupling.