Double-peak specific heat feature in frustrated antiferromagnetic clusters

TL;DR

This paper investigates the double-peak specific heat in kagome antiferromagnetic clusters, revealing that the low-temperature peak arises from a rapid increase in density of states just above the spin gap, with models explaining its weak magnetic field sensitivity.

Contribution

The study introduces simple models that explain the origin of the low-temperature specific heat peak in frustrated antiferromagnetic clusters, linking it to the density of states near the spin gap.

Findings

The low-$T$ peak is due to the rapid increase in density of states above the spin gap.

The models explain the weak magnetic field sensitivity of the low-$T$ peak.

The results are applicable to other frustrated antiferromagnetic systems.

Abstract

We study the nature of the double-peak specific heat structure in kagome clusters. That containing 12 spins is considered thoroughly by numerical diagonalization. Simple models are proposed revealing the low-$T$ peak nature at $T_l<\Delta$ ($\Delta$ is the spin gap) in this case and in those of larger clusters studied so far. We show that the rapid increase in density of states just above the spin gap gives rise to this peak. These models establish the reason for the weak magnetic field sensitivity of the low-$T$ peak. Our discussion could be appropriate for other frustrated antiferromagnetic systems too.