High magnetic field study of the specific heat of CeB6 and LaB6

The specific heats of CeB 6 and LaB 6 have been measured over a large range of temperatures and under magnetic fields up to 8 teslas. The data confirm that the intermediate phase of CeB 6 , the so-called phase II, is favoured by an applied magnetic field. Actually both the transition temperature and the associated specific heat anomaly are strongly increased by a magnetic field. To get the magnetic contribution from the CeB 6 specific heat with more accuracy, we have measured the non-magnetic compound LaB 6 . The analysis of this magnetic contribution confirms that the Ce 3+ ground state is the Γ 8 quartet, and the splitting with the Γ 7 doublet is estimated to be larger than 500 K Mesures dans un large domaine de temperatures et sous champ magnetique jusqu'a 8 T. Renforcement de la temperature de transition et de l'anomalie de chaleur massique dans CeB 6 en phase II intermediaire. Determination de la contribution magnetique a la chaleur massique de CeB 6 a partir des mesures de la chaleur massique de LaB 6 non magnetique. Confirmation d'un etat fondamental quadriplet Γ 8 pour Ce 3+