Magnetic properties of Gd-doped PbTe

Abstract

Electron paramagnetic resonance (EPR) and low-field ac susceptibility measurements were done on the rare-earth-doped semimagnetic semiconductor PbGdTe for the Gd composition range 100 ppm–10 at.%. For the lower concentrations, the EPR results indicate a fully resolved fine structure appropriate to the Gd3+ ion and g values close to the free-electron value. Susceptibility results show Curie–Weiss behaviour in all samples for temperatures above 10 K, small negative Curie temperatures, and Peff values corresponding to a Gd spin of 7/2. Deviations from this simple behaviour are observed for Gd concentrations greater than 5 at.% and for temperatures below 10 K. Evidence is observed for an antiferromagnetic clustering of impurity spins.