Volume Effect in Thermal Properties of CeRu2Si2near the Metamagnetic Crossover

Abstract

Volume effect in the temperature and field variation of the specific heat C ( T , H ) of CeRu 2 Si 2 was examined by means of detailed thermal expansion measurement performed at temperatures T ≥1.5 K in magnetic fields H ≤78 kOe. Making use of thermodynamic relations and the scaling properties that hold in the system, the specific heat C V at constant volume is estimated from experimental values of C P at constant pressure. We show that the double-peak structure in C P / T vs. H curve, recently observed by Aoki et al. across the metamagnetic critical region, still remains in the constant volume condition; it is likely to be intrinsic in origin. We have also examined the thermal expansion of the diluted system Ce 0.85 (La 0.63 Y 0.37 ) 0.15 Ru 2 Si 2 where metamagnetism is absent. Remarkable difference in the field variation of the thermal expansion coefficient between these two systems below 10 K demonstrates the existence of a low energy scale that arises from certain inter-site effect and is relevant fo...