SEMI-SPIN-GLASS AND SPIN-GLASS BEHAVIOR IN EUXSR1-XSE WITH X = 0.5 AND 0.7

We have investigated the linear and, in detail, the non-linear AC susceptibilities of two insulating spin glasses obtained from the dilution of the antiferromagnetic EuSe with diamagnetic SrSe. The systems studied are the mixed compound EuxSr1-xSe with x = 0.5 and 0.7. The linear susceptibilities of the samples show a single peak at their spin-glass freezing temperatures of 2.00 +/- 0.03 K and 2.88 +/- 0.03 K, respectively. However, the non-linear susceptibilities (third harmonics) of the systems exhibit double peaks: one at the spin-glass transition temperature, and the other at a higher temperature somewhat below the Neel temperature of pure EuSe which is 4.6 K. We believe that the origin of the second peak is the remaining antiferromagnetic phase which seems to persist in the systems down to a critical concentration below x = 0.5.