Magnetic susceptibility and EPR measurements in concentrated spin-glasses: Cd1−xMnxTe and Cd1−xMnxSe

Abstract

We have measured the magnetic susceptibility and the electron paramagnetic resonance for ${\mathrm{Cd}}_{1-x}{\mathrm{Mn}}_x\mathrm{Te}(0.001\mathrm{}\le x\le 0.60)$ and ${\mathrm{Cd}}_{1-x}{\mathrm{Mn}}_x\mathrm{Se}(0.001\mathrm{}\le x\le 0.45)$ as a function of magnetic field, temperature, time, and microwave frequency. For $x<\mathrm{}0.20\mathrm{}$, both systems remain paramagnetic for all temperatures measured ($0.7\le T\le 300$ K). Above $x\simeq 0.20$, a cusp in the low-field susceptibility after zero-field cooling was observed at a temperature $T_f$, its position being a linear function of concentration. A broadening and a shift in the magnetic field of the electron paramagnetic resonance line with decreasing temperature were observed, and found to be independent of the microwave frequency used (9 and 35 GHz). The isothermal remanent and thermoremanent magnetization were studied in detail. The magnetic properties of these systems are similar to those of the canonical metallic spin-glasses, with the exception that the scaling law for the magnetization is not obeyed.