Susceptibility and Low Temperature Thermodynamics of Spin-1/2 Heisenberg Ladders

TL;DR

This paper investigates the low-temperature magnetic susceptibility and ground state energy of antiferromagnetic Heisenberg ladders with up to six legs, revealing differences between even and odd-leg ladders and their dependence on coupling ratios.

Contribution

It provides detailed Monte Carlo calculations of susceptibility and energy for multi-leg ladders, highlighting spin gap behavior and low-temperature corrections.

Findings

Even-leg ladders exhibit spin gaps at low temperatures.

Odd-leg ladders have finite susceptibility as temperature approaches zero.

Logarithmic corrections increase with the number of legs for equal couplings.

Abstract

The temperature dependence of the uniform susceptibility and the ground state energy of antiferromagnetic Heisenberg ladders with up to 6 legs has been calculated, using the Monte Carlo loop algorithm. The susceptibilities of even-leg-ladders show spin gaps while these of odd-leg-ladders remain finite in the zero temperature limit. For small ratios of intra- to inter-leg couplings, odd-leg-ladders can be mapped at low temperatures to single chains. For equal couplings, the logarithmic corrections at low temperatures increase markedly with the number of legs.