Magnetic phase diagrams of Ce 0.4La 0.6B 6 up to 15 T investigated by specific heat measurements

Abstract

Transition temperature between phase I (paramagnetic phase) and II (antiferro-quadrupolar ordered phase), T Q, in magnetic fields up to 15 T is investigated for a high-quality single-crystal Ce 0.4La 0.6B 6 by specific heat measurements. For H||〈0 0 1〉 T Q increases with magnetic field up to ∼12 T, as is known for larger x. However, T Q shows a decrease with magnetic field above ∼12 T, which indicates that phase II closes in the H– T plane. While in H||〈1 1 0〉 T Q continues to increase with magnetic field up to ∼15 T and remarkable anisotropy of the phase boundary in the high-field region is revealed.