MAGNETIC PHASE-DIAGRAM OF THE TRIANGULAR LATTICE ANTIFERROMAGNET ABX3 UNDER HIGH MAGNETIC-FIELD

Our recent experimental study on the magnetic phase diagrams of stacked triangular lattice antiferromagnets (TAL-AF) is summarized. The precise magnetization measurements in the temperature range between 1.4 and 20 K under static magnetic fields up to 12 T have revealed that the magnetic field versus temperature phase diagrams of the ABX3 compounds are classified into two types depending on the difference in their magnetic anisotropies in agreement with the theoretical prediction. In the case of the XY TAL-AF, CsMnBr3 and RbMnBr3 with an easy plane anisotropy, only a single transition is observed at zero field but it splits into two successive transitions under finite fields in the basal plane. On the other hand, in the case of the Ising-like TAL-AF, CsNiBr3 and CsMnI3 with an easy axis anisotropy, two successive transitions are observed at zero field and these are merged into a single transition at the multicritical point under finite fields parallel to the c-axis and a line of the spin-flop transition also meets this point.