Magnetoelastic properties of a spin-1/2 Ising-Heisenberg diamond chain in vicinity of a triple coexistence point

TL;DR

This paper investigates how magnetoelastic coupling influences the ground state and thermal properties of a spin-1/2 Ising-Heisenberg diamond chain near a triple coexistence point, revealing unique entropy, heat capacity, and magnetization behaviors.

Contribution

It introduces a detailed analysis of magnetoelastic effects in a diamond chain model, highlighting the impact of lattice vibrations on magnetic and thermal properties near a critical point.

Findings

Presence of a low-temperature entropy plateau due to magnetoelastic effects

Anomalous peak in specific heat below the entropy plateau

Magnetization plateau at nearly saturated value before decreasing with temperature

Abstract

We study magnetoelastic properties of a spin-1/2 Ising-Heisenberg diamond chain, whose elementary unit cell consists of two decorating Heisenberg spins and one nodal Ising spin. It is assumed that each couple of the decorating atoms including the Heisenberg spins harmonically vibrates perpendicularly to the chain axis, while the nodal atoms involving the Ising spins are placed at rigid positions when ignoring their lattice vibrations. An effect of the magnetoelastic coupling on a ground state and finite-temperature properties is particularly investigated close to a triple coexistence point depending on a spring-stiffness constant ascribed to the Heisenberg interaction. The magnetoelastic nature of the Heisenberg dimers is reflected through a non-null plateau of the entropy emergent in a low-temperature region, whereas the specific heat displays an anomalous peak slightly below the temperature region corresponding to the entropy plateau. The magnetization also exhibits a plateau in the same temperature region at almost saturated value before it gradually tends to zero upon increasing of temperature. The magnetic susceptibility displays within the plateau region an inverse temperature dependence, which slightly drops above this plateau, whereas an inverse temperature dependence is repeatedly recovered at high enough temperatures.