Magnetic properties of Cd<i>x</i>Zn<i>y</i>Mn<i>z</i>Te alloys

Abstract

Low-field measurements of magnetic susceptibility χ have been made as a function of temperature in the range 4–150 K on polycrystalline samples of the alloy system CdxZnyMnzTe (x+y+z=1). Values of Tg, the spin-glass transition temperature, have been obtained from the cusp in the χ vs T curves and values of the Curie-Weiss θ obtained by extrapolation of the 1/χ vs T line at the higher temperatures. When the various values of Tg vs composition are fitted to a straight line they all extrapolate to a percolation limit of 0.18±0.01. However, it is shown that the plot proposed by Escorne et al. of ln Tg vs az−1/3, where a is the lattice parameter, also gives a straight line variation within the limits of experimental error. This indicates that for z≤0.2, the variation of Tg with z must deviate from linearity. The extrapolated value of 0.18±0.01 is attributed to nearest neighbors only and for z≤0.2 more distant neighbors become relatively more important. For both the Tg vs z and ln Tg vs az−1/3, a change in slope occurs at z≊0.6. This probably represents the change from spin glass to antiferromagnetic behavior and may be due to an additional exchange effect becoming important.