Magnetic field effects on two-leg Heisenberg antiferromagnetic ladders: Thermodynamic properties

TL;DR

This study uses the transfer-matrix renormalization group method to analyze how magnetic fields influence the thermodynamic behavior of two-leg antiferromagnetic ladders, revealing various quantum phases and explaining experimental observations.

Contribution

It applies a novel computational approach to characterize phase behavior in magnetic ladders, clarifying the origin of experimental phenomena in quasi-one-dimensional systems.

Findings

Identification of disordered spin liquid, Luttinger liquid, spin-polarized, and classical phases.

Divergence of NMR relaxation rate explained by quasi-one-dimensional effects.

Anomalous specific heat behavior attributed to low-dimensional quantum effects.

Abstract

Using the recently developed transfer-matrix renormalization group method, we have studied the thermodynamic properties of two-leg antiferromagnetic ladders in the magnetic field. Based on different behavior of magnetization, we found disordered spin liquid, Luttinger liquid, spin-polarized phases and a classical regime depending on magnetic field and temperature. Our calculations in Luttinger liquid regime suggest that both the divergence of the NMR relaxation rate and the anomalous specific heat behavior observed on Cu$_2$(C$_5$H$_{12}$N$_2$)$_2$Cl$_4$}are due to quasi-one-dimensional effect rather than three-dimensional ordering.