Muon spin relaxation study of spin-glass freezing in the Heusler compound Ru1.9Fe0.1CrSi

Abstract

In the temperature dependence of magnetization, the Heusler compound Ru${}_{1.9}$Fe${}_{0.1}$CrSi exhibits a peak at a temperature which is defined as ${T}_{N}^{*}$. Below that temperature strong irreversibility occurs, the onset temperature of which is defined as ${T}_{g}$. However, no evidence of long-range order has been found. In this study the magnetic properties of these anomalies were investigated using zero-field (ZF) and longitudinal-magnetic-field (LF) muon-spin-relaxation ($\ensuremath{\mu}$SR) measurements. In the temperature dependence of the relaxation rate of ZF-$\ensuremath{\mu}$SR, a peak at $\ensuremath{\sim}$16 K was observed, which agrees with ${T}_{g}$. LF-$\ensuremath{\mu}$SR measurements as a function of magnetic field reveal the existence of a static internal magnetic field at 0.3 K. Around ${T}_{N}^{*}\ensuremath{\sim}30$ K, we detected no anomalies that can be associated with a magnetic phase transition in the temperature dependence of the relaxation rate of $\ensuremath{\mu}$SR, but a large decrease in the initial asymmetry was observed. LF-$\ensuremath{\mu}$SR measurements suggest that the internal magnetic field appears even around ${T}_{N}^{*}$. These results suggest that around ${T}_{N}^{*}$ independent spin-frozen regions form inhomogeneously. With decreasing temperature these regions gradually develop, and eventually, at ${T}_{g}$ spin-glass freezing occurs with correlations over the whole sample.