Fingerprints of cluster-based Haldane and bound-magnon states in a spin-1 Heisenberg diamond chain

TL;DR

This study explores the complex magnetic phases of a spin-1 Heisenberg diamond chain, revealing novel quantum states and their potential for efficient quantum heat engine applications through combined analytical and numerical methods.

Contribution

It identifies and characterizes new quantum phases in the frustrated spin-1 diamond chain, including Haldane and bound-magnon states, using a comprehensive multi-method approach.

Findings

Discovery of unconventional quantum phases including Haldane and bound-magnon states.

Enhanced magnetocaloric effect near phase transitions.

Potential application as a quantum Stirling engine with high efficiency.

Abstract

We investigate magnetic and thermodynamic properties of a spin-1 Heisenberg diamond chain in a magnetic field using a combination of analytical and numerical methods including the variational approach, exact diagonalization, density-matrix renormalization group, localized-magnon theory, and quantum Monte Carlo simulations. In the unfrustrated regime, the model exhibits a quantum ferrimagnetic phase that captures key magnetic features of the nickel-based polymeric compound [Ni3(OH)2(C4H2O4)(H2O)4].2H2O such as a at minimum in the temperature dependence of the susceptibility times temperature product and an intermediate one-third magnetization plateau. In the frustrated regime, we uncover a rich variety of unconventional quantum phases including uniform and cluster-based Haldane states, fragmented monomer-dimer phase, and bound-magnon crystals. Analysis of the adiabatic temperature change and magnetic Gruneisen parameter reveals an enhanced magnetocaloric effect near field-induced transitions between these exotic quantum phases. Additionally, we demonstrate that the frustrated spin-1 diamond chain can operate as an efficient working medium of a quantum Stirling engine, which approaches near-optimal efficiency when driven into these unconventional quantum states.