Ordered Phases and Phase Transitions in The Stacked Triangular Antiferromagnet CsCoCl₃and CsCoBr₃

Abstract

We study the ordered phases and the phase transitions in the stacked triangular antiferromagnetic Ising (STAFI) model with strong interplane coupling modeling CsCoCl 3 and CsCoBr 3 . We find that there exists an intermediate phase which consists of a single phase of so-called partial disordered (PD) type, and confirm the stability of this phase. The low temperature phase of this model is so-called two-sublattice ferri magnetic phase. The phase transition between the PD phase and two-sublattice ferri magnetic phase is of the first order. This sequence of the phases is homomorphic as that in the threedimensional generalized six-state clock model which have the same symmetry of the STAFI model. By studying distributions of domain walls in one dimensional chains connecting layered triangular lattices, we clarify the nature of the phase transition and give an interpretation of little anomaly of the specific heat.

Magnetism and Transport Phenomena in Spin-Charge Coupled Systems on Frustrated Lattices

“…1.13a) is realized in the finite temperature region in between the low temperature FR ordered state and the high-temperature paramagnetic phase. So far, the only PD state confirmed is in a threedimensional model with stacked triangular lattices, in which the interlayer spin-spin coupling being stronger than the intralayer couplings [54]. In a series of the subsequent studies, the phase diagram of this model was studied extensively using the classical MC simulation for both weak J 2 [11-13, 49, 57] and for J 2 being comparable to J 1 [24].…”

Phase Diagram of Lattice–Spin System RbCoBr3

“…The magnetic 3FR state does not appear when the lattice is not distorted. 6) Lattice and spin degrees of freedom and nonequivalence interactions induce the appearance of (3FR, 3FR) phase.…”

“…A large number of experimental and theoretical studies have been carried out for hexagonal ABX 3 -type substances such as CsCoCl 3 and CsCoBr 3 because of the successive magnetic phase transitions due to the strong spin frustration. [1][2][3][4][5][6] These substances consist of quasione-dimensional spin chains because the intrachain antiferromagnetic exchange interaction is much stronger than the interchain antiferromagnetic exchange interaction. Substances of this type are expressed by the stacked triangular antiferromagnetic Ising model.…”

Partial Disorder in an Ising-Spin Kondo Lattice Model on a Triangular Lattice

“…Although such PD state was indeed observed in several Co compounds [5,6], subsequent Monte Carlo (MC) simulations indicated that, in purely two-dimensional systems, the PD appears at most as a quasi-LRO and that the transition from the high-T paramagnetic phase is of Kosterlitz-Thouless (KT) type [7][8][9][10][11][12]. The results suggest that, for establishing a PD LRO, it is indispensable to incorporate additional elements, such as a three-dimensional interlayer coupling [13].In this Letter, we explore the possibility of PD LRO in two dimensions when taking account of the coupling to itinerant electrons. Our study is partly motivated by the recent discovery of PD in metallic compounds with quasi-two-dimensional structure [14].…”