Spin Stiffness of Mesoscopic Quantum Antiferromagnets

TL;DR

This paper investigates the spin stiffness in one-dimensional quantum antiferromagnets, revealing fundamental differences based on spin type and system size, with implications for understanding quantum magnetic properties.

Contribution

It provides a comprehensive analysis of spin stiffness across all system sizes and temperatures, highlighting differences between integer and half-odd integer spins using different theoretical models.

Findings

Spin stiffness depends fundamentally on system size and temperature.

Half-odd integer spin chains show parity-dependent stiffness behavior.

Integer spin chains are modeled with the non-linear sigma model.

Abstract

We study the spin stiffness of a one-dimensional quantum antiferromagnet in the whole range of system sizes $L$ and temperatures $T$. We show that for integer and half-odd integer spin case the stiffness differs fundamentally in its $L$ and $T$ dependence, and that in the latter case the stiffness exhibits a striking dependence on the parity of the number of sites. Integer spin chains are treated in terms of the non-linear sigma model, while half-odd integer spin chains are discussed in a renormalization group approach leading to a Luttinger liquid with Aharonov-Bohm type boundary conditions.