Magnetic phase diagrams of [formula omitted] in high magnetic fields

Abstract

We have performed ultrasonic measurements under high magnetic fields up to 30 T by using the hybrid magnet at the National Institute for Materials Science to investigate the magnetic phase diagram for antiferroquadrupole (AFQ) phase II in Ce x La 1 - x B 6 . With increasing Ce concentration x from x = 0.50 , the AFQ phase transition temperatures T Q indicate an almost linear increase in various fields. The large magnetic anisotropy of AFQ phase II, in which T Q H ∥ [ 0 0 1 ] is much smaller than T Q H ∥ [ 1 1 0 ] and T Q H ∥ [ 1 1 1 ] in high magnetic fields, is revealed in x = 0.75 , 0.60 as well as in x = 0.50 . These experimental results support the theoretical calculation based on the Γ 5 -type AFQ ordering and the magnetic field induced octupole T xyz .