Thermal and magnetic properties of spin-1 magnetic chain compounds with large single-ion and in-plane anisotropies

TL;DR

This paper investigates the thermal and magnetic behaviors of spin-1 chain compounds with large anisotropies using integrable models, revealing new phases and transitions, and matches theoretical results with experimental data.

Contribution

It introduces an exact integrable model approach to analyze anisotropic spin-1 chains, uncovering novel phases and phase transitions not previously characterized.

Findings

Large single-ion anisotropy induces a singlet gapped phase.

In-plane anisotropy can eliminate the gapped phase.

Theoretical results agree well with experimental measurements.

Abstract

The thermal and magnetic properties of spin-1 magnetic chain compounds with large single-ion and in-plane anisotropies are investigated via the integrable su(3) model in terms of the quantum transfer matrix method and the recently developed high temperature expansion method for exactly solved models. It is shown that large single-ion anisotropy may result in a singlet gapped phase in the spin-1 chain which is significantly different from the standard Haldane phase. A large in-plane anisotropy may destroy the gapped phase. On the other hand, in the vicinity of the critical point a weak in-plane anisotropy leads to a different phase transition than the Pokrovsky-Talapov transition. The magnetic susceptibility, specific heat and magnetization evaluated from the free energy are in excellent agreement with the experimental data for the compounds NiC_2H_8N_2)_2Ni(CN)_4 and Ni(C_{10}H_8N_2)_2Ni(CN)_4.H_2O.