Measurements of critical magnetic fields and resistance for sigma phase Mo-Re

Measurements of the critical magnetic fields and the electrical resistance for sigma phase alloys of the Mosub(1-x)Resub(x) (0.55 <= x <= 0.7) system are reported. The variation of Tsub(c) lies within 0.5 K for various compositions and heat treatments. The extrapolated upper critical magnetic fields Hsub(c2)(0) are between 22.6 and 36.0 kG. A splat-quenched alloy of composition Mo-62at.%Re has an Hsub(c2)(0) value of 27.1 kG. Thus atomic disorder does not influence Hsub(c2)(0) significantly. The Hsub(c2)(0) values agree in general with the calculated Hsub(c2)(0) values where paramagnetic effects have been included. The resistance ratio varies as T3 in the low temperature region, then has a negative curvature (50 - 150 K) and the curve is less than linear in T at temperatures above 150 K. This behaviour is similar to that of many other d and f band superconductors and can be explained by a modified s-d model. (Auth.)