Peculiar Magnetic and Transport Properties of CuFeS2: Defects Play a Key Role

Abstract

Our study targets some of the long-standing questions concerning the somewhat mysterious properties of chalcopyrite CuFeS2. We show that defect chemistry in connection with charge transfer within the structure is responsible for the unusual electronic and magnetic properties of CuFeS2. Specifically, our model addresses weak ferromagnetism and the high mobility of carriers on the background of a rigid antiferromagnetic structure. We show that defect structure can, counterintuitively, boost the mobility of free carriers due to defect-modified charge transfer. Further, the defect-modified charge transfer induces the weak ferromagnetism both in the Cu- and Fe-sublattice. This new view opens up space for further investigations and applications of charge transfer compounds.