Abstract
Nuclear magnetic resonance studies on Mn 55 in α-Mn metal and Mn-Cr alloys which have an α-Mn phase in the temperature range around the Neel transition point, have been made by a pulse method. Nuclear spin-spin relaxation time T 2 has shown discontinuity at the Neel temperature, T N . The T 2 values are well proportional to ( T N - T ) 1/3 in antiferromagnetic state and to ( T - T N ) 2/8 in paramagnetic state. The measured values of T N in α-Mn metal, Mn- 1 at.% Cr, and Mn- 2 at.% Cr alloys determined by nuclear magnetic resonance method are 95.0±1.0°K, 81.6±1.0°K, and 72.3±0.5°K, respectively. Mn- 5 at.% Cr alloy did not show an antiferromagnetic behaviour even at 4.2°K. T N decreases with Cr content, but increases with Fe content. These results suggest that the rigid-band model is a good approximation for these metal alloy systems.
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