Magnetic and electrical properties of cation-substituted sulfides Me x Mn1 − x S (Me = Co, Gd)

Abstract

The temperature dependences of the specific magnetization σ and the electrical resistivity ρ of Me x Mn1 − x S single crystals (Me= Co, Gd; x= 0.05) have been studied in the temperature range 80 K < T < 1000 K. The samples under study have revealed the presence of a spontaneous magnetic moment below the Néel temperature (T N) and ferromagnetic clusters in Gd0.05Mn0.95S in the temperature range 146 K < T < 680 K. Substitution of gadolinium for manganese initiates a transition from p-type to n-type conduction. The change in the conduction type is accompanied by an increase in the electrical resistivity at 300 K by approximately one order of magnitude and, accordingly, by a decrease in the activation energy. The magnetic and electrical properties of the crystals under study have been interpreted in terms of the cluster model with temperature-dependent ferromagnetic exchange and an electron localized in this cluster.