Critical dynamics inCd1−xMnxTe spin glasses

Abstract

The critical dynamics in ${\mathrm{Cd}}_{1\mathrm{-}\mathit{x}}$ ${\mathrm{Mn}}_{\mathit{x}}$Te is investigated by accurate Faraday rotation measurements carried out in the vicinity of the freezing temperature on compounds of composition x=0.38 and x=0.50. The temperature dependence of the average relaxation time is well described by conventional power law, for critical temperatures ${\mathit{T}}_{\mathit{c}}$=9.9±0.1 K (x=0.38) and ${\mathit{T}}_{\mathit{c}}$=17±0.1 K (x=0.50). The validity of the dynamic scaling law for the imaginary part of the complex susceptibility is tested using the χ’ ’(T,ω) data obtained in the entire temperature and frequency range. The best scalings performed for the above ${\mathit{T}}_{\mathit{c}}$ values yield a dynamic exponent zν=9±1 and an order-parameter exponent β=0.6±0.1 for both investigated compounds. The observation of a unique scaling function in the composition range 0.3–0.5 supports the existence of universality.