Estimation of magneto-crystalline uniaxial anisotropy constant of β-FeOOH by Mössbauer spectroscopy

Abstract The magneto-crystalline uniaxial anisotropy constant, K u , of β-FeOOH was estimated by analyzing temperature dependence of Mossbauer absorption spectra taking into account the thermal relaxation of the internal magnetic fields. It was deduced to be 2.1 × 10 3 J/m 3 , using a typical volume (9 × 10 −24 m 3 ) of synthesized β-FeOOH particles observed by TEM. The value, K u of β-FeOOH is in the same order but twice as large as that of α-FeOOH, 1 × 10 3 J/m 3 .