Finite-temperature crossover phenomenon in the $S=1/2$ antiferromagnetic Heisenberg model on the kagome lattice

TL;DR

This study explores the thermal behavior of the $S=1/2$ kagome Heisenberg antiferromagnet, revealing multiple peaks in specific heat and a crossover between different magnetic short-range orders at low temperatures.

Contribution

It provides detailed numerical analysis of finite-temperature properties and identifies a crossover phenomenon between distinct spin-liquid states in the kagome lattice.

Findings

Multiple peaks in specific heat at low temperatures.

Crossover from $ ext{sqrt{3} imes ext{sqrt{3}}}$ to $q=0$ magnetic SRO.

Association of the third specific heat peak with the crossover phenomenon.

Abstract

Thermal properties of the $S=1/2$ kagome Heisenberg antiferromagnet at low temperatures are investigated by means of the Hams-de Raedt method for clusters of up to 36 sites possessing a full symmetry of the lattice. The specific heat exhibits, in addition to the double peaks, the third and the forth peaks at lower temperatures. With decreasing the temperature, the type of the magnetic short-range order (SRO) changes around the third-peak temperature from the $\sqrt{3} \times \sqrt{3}$ to the $q$=0 states, suggesting that the third peak of the specific heat is associated with a crossover phenomenon between the spin-liquid states with distinct magnetic SRO. Experimental implications are discussed.