Mössbauer Study of Fe1-xCrx Alloys

The internal field H int at 57 Fe nuclei in Fe 1- x Cr x alloys has been measured at 4.2 K and 1.7 K in the concentration range 0≤ x ≤0.96 by means of the Mossbauer effect. In the concentration range 0≤ x ≤0.93, H int varies almost linearly with increasing x from the value 340 kOe at x =0 to 120 kOe at x =0.93. As for alloys Fe 0.15 Cr 0.85 and Fe 0.13 Cr 0.87 , the temperature dependence of the internal field has been examined from 300 to 4.2 K. In each of both alloys, the field vs temperature curve shows two plateaus around 40 K and 4 K, having respectively values of 35 and 120 kOe. This suggests that the magnetic moments of Fe in the alloys thermally fluctuate above 30 K, and the observed field of 35 kOe is mainly ascribed to the magnetic moments of Cr ordered in an antiferromagnetic state, while the magnetic moments of Fe become ordered below 30 K, producing the larger internal field of about 120 kOe at 4.2 K.