NOVEL ZERO-GAP COMPOUNDS, MAGNETICS - CUFES2 AND CUFETE2

The temperature dependences of the Hall coefficient R(T), specific con ductivity sigma(T), and electron concentration n(T) of CuFeS2 and CuFe Te2 monocrystals are investigated. From their power dependences the ze ro bandgap for the electron excitations of these substances is establi shed. Analysis of the temperature dependence of the mobility mu(T) ena bles us to conclude that the conduction electrons are in the magnetopo laron (ferron) state of large and small radius in CuFeS2 and CuFeTe2 r espectively. The existence of various power dependences R(T), sigma(T) and n(T) in CuFexAl1-xS2 solid solutions, in the CuFeS2 compound, whi ch is under pressure, and in the CuFeTe2 compound, is pointed out. The se anomalies are explained both by the manifestation of peculiarities of the ferron spectrum and by various mechanisms of ferron mobility. I t is pointed out that the theoretical group analysis of the CuFeS2 str ucture corroborates the possibility of the existence of the zero-gap s tate at the P point of the Brillouin zone. Some peculiarities of the z ero-gap spectra of the both substances are discussed.