Spin-glass behaviour in Sr2FeSnO6–y, studied by Mössbauer spectroscopy

Abstract

The cubic perovskite solid solution Sr₂FeSnO_5.71, which contains both Fe³⁺ and Fe⁴⁺ cations, has been shown to be a spin-glass by a combination of magnetic susceptibility with ⁵⁷Fe and 119Sn Mössbauer spectroscopic measurements. The zero-field-cooled and field-cooled magnetic susceptibility diverge below a temperature of 15 ± 2 K, and a relaxational collapse of the Mössbauer magnetic hyperfine splitting with rise in temperature is complete by 26 ± 2 K. The transferred hyperfine nteractions in the ¹¹⁹Sn resonance at 4.2 K give evidence to support the existence of randomly oriented spin moments. The composition Sr₂FeSnO_5.50 which can be obtained by heating in vacuo contains only Fe³⁺ cations and shows magnetic relaxation in a similar temperature region. However, electron diffraction measurements give evidence for short-range cation ordering to produce a supercell of √2a_p×√2a_p× 2a_p, where a_p is the cubic perovskite lattice parameter, and the ¹¹⁹Sn spectrum at 4.2 K shows that there is a substantial but unidentified ordering of the tin and iron cations.