Spin-glass behavior inLa(Fe1−xMnx)11.4Si1.6compounds

Abstract

The magnetic properties of $\mathrm{La}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}{)}_{11.4}{\mathrm{Si}}_{1.6}$ $(0<~x<~0.08)$ compounds were investigated. A reentrant spin glass behavior for the sample with $x=0.06$ and a paramagnetic-to-spin glass transition for the sample with $x=0.08$ were observed. The spin-glass behavior for the sample with $x=0.08$ was systematically studied by the dc and ac measurements. $\ensuremath{\Delta}{T}_{f}(\ensuremath{\omega})/[{T}_{f}(\ensuremath{\omega})\ensuremath{\Delta}{\mathrm{log}}_{10}\ensuremath{\omega}],$ a possible distinguishing criterion to assert the presence of a spin-glass phase was 0.02 for the sample with $x=0.08.$ The frequency-dependent data turned out to be well described by the conventional critical slowing down law $\ensuremath{\tau}/{\ensuremath{\tau}}_{0}={\ensuremath{\varepsilon}}^{\ensuremath{-}\mathrm{zv}}.$ The fit to this critical slowing down law yielded the values ${\ensuremath{\tau}}_{0}{=10}^{\ensuremath{-}12}\mathrm{s},$ $zv=8.28,$ and the transition temperature ${T}_{\mathrm{SG}}=45.24\mathrm{K}.$ This spin-glass behavior in $\mathrm{La}({\mathrm{Fe}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}{)}_{11.4}{\mathrm{Si}}_{1.6}$ compounds is mainly ascribed to the competing interaction between the Fe-Fe ferromagnetic ordering and the Fe-Mn, Mn-Mn antiferromagnetic ordering.