Mössbauer studies in disordered (NiFe) 1− xCr x alloys

Abstract

The variation of hyperfine field, isomer shift and Curie temperature with chromium concentration has been studied for the alloys (NiFe) 1− x Cr x for x = 0, 5, 10 and 15 at .%. The decrease in hyperfine field and isomer shift suggests an emptying of the majority spin d-band with increasing Cr concentration (reducing number of average 3 d + 4 s electrons per atom). The Curie temperature is also found to reduce rapidly with Cr concentration in agreement with magnetisation data. But the Curie temperatures as determined from Mössbauer spectra are considerably lower than those given by magnetisation studies and for the 10 and 15 at .% Cr concentrations the magnetic transition is spread out over a range of temperatures suggesting a mictomagnetic behaviour.