Spin-glass behaviour in Sr2FeSnO6–y, studied by Mössbauer spectroscopy
Abstract
The cubic perovskite solid solution Sr2FeSnO5.71, 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 Sr2FeSnO5.50 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 √2ap×√2ap× 2ap, where ap 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.