MAGNETIC GRUNEISEN PARAMETERS IN CR ALLOYS

The Stoner-Wohlfarth (SW) and Gruneisen-Testardi (GT) methods for analysing and parametrising the magnetic contributions to the thermal expansion and the bulk modulus of weak magnetic systems are compared. The GT theory is employed to analyse the magnetoelastic data for Cr alloy spin-density-wave systems, which had previously been treated by use of the SW theory. In Cr-Mo the magnetic Gruneisen parameters, Gamma SF in the paramagnetic phase and Gamma NT in the ordered state, decrease monotonically as the Mo concentration increases up to about 10 at.%. In Cr-Al, on the other hand, Gamma SF, and Gamma SW at zero temperature, show a gigantic peak centred at about the composition, Cr+2.2 at.% Al, close to the tripole point, while Gamma NT is roughly constant throughout the singular region. General features of the behaviour of the magnetic Gruneisen parameters, as functions of solute concentration in Cr alloy systems, and in pure Cr, are discussed.