The metal-insulator transition in magnetic semiconductors: Transport in Gd_-xv_xS₄

This note reviews magnetotransport data on the magnetic semiconductor Gd-xvxS4 (v = vacancy). New data on the metallic side of the transition are presented. The results for two samples may be summarized as follows: 1) At low temperatures (T ∼ 10 mK) the conductivity, σ(0) ∝ (H Hc), where Hc is a critical field below which the material is an insulator; 2) for the sample with the larger critical field, the data are not consistent with variable range hopping: 3) for H/Hc ≳ 1, the temperature dependence deviates only little from a √T law. © 1985.