Thermodynamic properties of an integrable quantum spin ladder with boundary impurities

TL;DR

This paper investigates the thermodynamic properties of an integrable SU(4) quantum spin ladder with boundary impurities, analyzing energy spectra and magnetic responses near critical points using the Bethe ansatz.

Contribution

It introduces new boundary impurity solutions in an SU(4) integrable spin ladder and computes their thermodynamic and magnetic properties.

Findings

Derived susceptibility and magnetization near critical points.

Identified magnetic differences between antiferromagnetic and ferromagnetic impurities.

Applicable to real ladder compounds like Cu2(C5H12N2)2Cl4.

Abstract

An integrable quantum spin ladder based on the SU(4) symmetry algebra with boundary defects is studied in the framework of boundary integrability. Five nontrivial solutions of the reflection equations lead to different boundary impurities. In each case the energy spectrum is determined using the quantum inverse scattering method. The thermodynamic properties are investigated by means of the thermodynamic Bethe ansatz. In particular, the susceptibility and the magnetization of the model in the vicinity of the critical points are derived along with differing magnetic properites for antiferromagnetic and ferromagnetic impurity couplings at the edges. The results are applicable to the strong coupling ladder compounds, such as Cu_2(C_5 H_12 N_2)_2 Cl_4.