EVIDENCE FOR THE EXISTENCE OF 2 ELECTRONIC STATES IN THE CHALCOPYRITE-TYPE ALLOYS CUFE(S1-ZSEZ)(2)

Results of Mossbauer spectroscopy for the chalcopyrite-type of alloys CuFe(S1-zSez)(2) in the range of composition 0 less than or equal to z less than or equal to 0.45 are presented. Room temperature spectra sh ow two contributions: one is a magnetic spectrum (six lines) with a va lue of the hyperfine field near to that of chalcopyrite (z = 0, in whi ch an antiferromagnetic order occurs below T = 823 K), the other havin g only one line. The relative area of the single-line contribution inc reases as z increases. For z = 0.2, we also made Mossbauer measurement s as a function of temperature. The ratio of the two contributions evo lves according to a Boltzmann law, in which the single line correspond s to the excited state at 81 K above the antiferromagnetic ground stat e.