THE TEMPERATURE-DEPENDENCE OF THE ITINERANT-ELECTRON METAMAGNETIC TRANSITION IN LAVES-PHASE LU(CO1-XGAX)2 COMPOUNDS

The high-field magnetization and temperature dependence of the critical field have been investigated for Laves-phase Lu(Co1-xGax)2 compounds. A clear itinerant-electron metamagnetic transition is observed and its critical field increases with increasing temperature for x = 0.09. The results are discussed on the basis of the Clausius-Clapeyron equation for the magnetic phase transition. This reveals that the magnetic entropy of these compounds decreases above the critical field, suggesting the suppression of the spin fluctuations due to the metamagnetic transition. This is consistent with the recent results on the field dependence of the electronic specific-heat coefficient of these compounds. The Arrott plots for the specimen with x = 0.12, which has a very low critical field, have also been investigated. The squared hypothetical spontaneous magnetization M(h)2 decreases linearly with increasing T2 and the reduced M(h) versus T plot for Lu(Co0.88Ga0.12)2 is very similar to the reduced magnetization for an Invar-type ferromagnetic Lu(Cu0.83Al0.17)2 compound. This results suggests that Lu(Co0.88Ga0.12)2 in the ferromagnetic state is expected to exhibit marked magnetovolume effects.