Gapless State in CuFeS₂

Abstract

Abstract A theoretical group analysis of the CuFeS 2 structure is made in the presence of magnetic order. It is shown that in such a structure a gapless state may obtained at a point P of the Brillouin zone of chalcopyrite. The existence of ferron states is pointed out. A construction is made of a ferron state corresponding to the specified irreducible representation of the wave vector group of point P of the Brillouin zone. As a result of the analysis the conclusion is made that CuFeS 2 refers to gapless magnetic semiconductors where the gapless state is materialized at the boundary of the Brillouin zone and corresponds to a special case of spatial symmetry. In addition, the gapless state appears to be implemented not in usual but in ferron bands. The existence of a ferron hole is predicted. It is pointed out that the gapless state in CuFeS 2 corresponds to the first type gapless state according to the character of the temperature dependence of concentration.