Magnetic anisotropy of the antiferroquadrupole phase in Ce0.50La0.50B6 -: art. no. 156409

Magnetic phase diagrams for antiferroquadrupole (AFQ) phase II and antiferromagnetic (AFM) phase III in Ce0.50La0.50B6 with a Gamma(8) ground state have been investigated by ultrasonic measurements. The hybrid magnet (Gama) in the National Institute for Materials Science was employed for high-field measurements up to 30 T and a He-3-He-4 dilution refrigerator was used for low-temperature experiments down to 20 mK. The phase boundary from paramagnetic phase I to AFQ phase II under [001] magnetic fields closes at H(I-II)similar to29 T, while the boundary is still open under fields along the [110] and [111] directions even up to 30 T. This anisotropic character of phase II in fields is consistent with the theoretical calculation based on the O-xy-type AFQ ordering. We also found that AFM phase III reduces considerably in fields turning from the [001] to [110] and [111] directions.