Low-temperature transport properties of Cd0.91Mn0.09Te:In and evidence for a magnetic hard gap in the density of states

Abstract

A family of resistivity curves, with different carrier concentrations, is obtained in a single sample of the dilute magnetic persistent photoconductor Cd0.91Mn0.09Te:In. These curves exhibit a crossover from an exp(T0/T)1/2 form for variable-range hopping with interactions to an exp(EH/T) form, upon reducing temperature. All data scale onto a single curve. The energy EH is associated with a hard gap in the density of states which is magnetic in origin. The localization length is found to have the same critical behavior as the dielectric constant, on approaching the insulator-metal transition. © 1992 The American Physical Society.