Classical spin-liquid behavior in interactionally distorted antiferromagnetic spin systems on the kagome lattice

Abstract

The influence of an interaction distortion of the antiferromagnetic system on the kagome lattice on its magnetic and thermodynamic properties is investigated in the framework of the antiferromagnetic J1−J2−J3 spin-1/2 Ising system with three different nearest-neighbor antiferromagnetic interactions on the star kagome-like recursive lattice. The exact solution of the model is found and the phase diagram is determined and analyzed. It is shown that, depending on the model parameters, three antiferromagnetic phases can be identified, which are separated from the paramagnetic phase by the second order phase transitions. The magnetic and entropy properties of all ground states of the model are determined. Three different ground states that arise from the paramagnetic phase in the zero-temperature limit are identified. Due to the frustration, each of these ground states is highly macroscopically degenerated with different values of the residual entropy. In addition, since the paramagnetic phase in the vicinity of these ground states also exhibits high degeneracy with the presence of strong correlations, related to the proximity of the second-order phase transitions, these ground states together with their immediate paramagnetic surroundings can be considered as regions with the classical spin-liquid behavior. It is also shown that the typical anomalous (Schottky-type) behavior of the specific heat with the existence of a two-peak (in general multi-peak) structure in its temperature dependence in the vicinity of the highly macroscopically degenerated ground states can be suppressed by the presence of the second-order phase transitions.