11B NMR study of Ce0.75La0.25B6

Abstract We have carried out a 11 B NMR experiment on a single crystal of Ce 0.75 La 0.25 B 6 in order to elucidate the nature of phase IV. The NMR spectrum undergoes an appreciable broadening by an internal magnetic field as T is lowered in phase IV. Also, the nuclear spin-lattice relaxation rate, 1/ T 1 , exhibits a sharp peak around 1.7 K which is close to the phase I–IV transition point, originating from critical magnetic fluctuation towards a magnetic phase transition. These obtained results support the view that phase IV is considered to be a kind of magnetically ordered state.