The metal insulator transition in the magnetic semiconductor: Gd3−xvxS4 (invited; abstract)

Abstract

It is possible to tune through the metal insulator phase transition in the magnetic semiconductor Gd3−xvxS4 (where v=vacancy) by applying a magnetic field H. Contrary to similar effects observed in some ordinary semiconductors, the magnetoresistance is negative,1,2 indicating that the electronic states become more extended with increasing field. Here we present new transport measurements on samples with x=0.321 and 0.325, including the temperature dependence of the magnetoresistance near the phase transition. The principal result of the present study is that the transition is continuous in field. The low temperature conductivity, σ(T→0), obeys a linear relationship of the form σ(T→0)∝(H−Hc), which implies σ(T→0)∝(E−Ec), where Hc is a critical field and Ec is the mobility edge. Such behavior, in this analogue of a compensated semiconductor, is consistent with new scaling theories of both localization and interaction effects.