Zero-field muon-spin-relaxation depolarization rate of paramagnets near the Curie temperature

Abstract

The paramagnetic critical zero-field muon-spin-relaxation damping rate for cubic ferromagnets with dipolar interactions is computed by mode-coupling theory. We show that the temperature behavior of the damping rate is determined by the relative weight of the hyperfine interaction and the dipolar interaction between the muon magnetic moment and the lattice ion magnetic moments. A quantitative interpretation of the experimental data recorded on metallic Ni and Fe is given. Predictions are made for EuO and EuS.