Phase Transitions in the Frustrated ABX₃ Compounds

Abstract

In connection with the spin frustration, the phase transitions of hexagonal ABX3 compounds are experimentally studied. For the XY-like CsMnBr3, it is revealed that the phase transition belongs to a new universal class governed by Z2×S1 symmetry. It is also revealed that though the phase transition is well established, the ordered phase in this substance as well as the intermediate phases in the Ising-like CsCoCl3, CsCoBr3 and CsNiCl3 dynamically fluctuate in a time scale slightly longer than the observation time of neutron diffraction. Crucial effects of strong one-dimensionality of the substances are discussed.

Crossover to chirality in the critical behavior of the easy-axis antiferromagnetCsNiCl3

“…If the anisotropy of the magnetic ions is of easy-plane type CYF-like), the spins form a 120° structure in the basal plane, and the antiferromagnetic phase transition belongs to the n = 2 chiral universality class, whereas for systems without single-ion anisotropy, the transition is governed by the «=3 (Heisenberg) chiral universality class. One well-examined example for the easy-plane case is CsMnBr3 [3][4][5], where a =0.4 ±0.05. The Heisenberg case is found, e.g., in VBr2, which exhibits a =0.25+ 0.1 [6].…”