Magnetic semiconductors with Curie point above 300 K in the system of the solid solution Cu xMn 1−xCr 2S 4

Abstract

The magnetic and electric properties of the system of solid solution Cu x Mn 1− x Cr 2S 4 with x = 0, 0.1, 0.2 have been studied. It has been found that the addition of copper into the ferrimagnetic (FIM) semiconductor MnCr 2S 4 results in a strong increase of the Curie temperature T C with the conservation of the semiconductor conductivity. For compositions with x = 0.1 and 0.2, T C is 386 and 398 K, respectively. Thus, we have found new nondegenerate semiconductors with magnetic ordering temperatures higher than room temperature. This strong increase in T C is assumed to be associated with the existence of a strong s-d exchange interaction in compounds with x = 0.1 and 0.2. The value of this interaction has been estimated to be AS ≈ 0.6 eV ( A is the integral of the s-d exchange, S is the Cr 3+ ion spin).