Temperature dependence of magnetovolume for Ni-Cr alloys near the critical composition for magnetism

Abstract

Measurements of the low-temperature thermal expansion coefficient, α, of Ni-Cr alloys close to the critical concentration, x _c, for the ferromagnetic regime may be represented in the form α= A+BT+CT ³. The value for A increases in magnitude as x _c is approached and abruptly changes sign at x _c, being positive in the paramagnetic alloys and negative in the ferromagnetic alloys. Further measurements are reported that support a qualitative description proposed to account for the sign change in A, which is based upon a correspondence between the magnetovolume and the magnitude of the ordered magnetic moment and the moment fluctuation associated with the magnetic transition.