Electron Spin Resonance in a Spin-1/2 Heisenberg Strong-rung Ladder

TL;DR

This study uses ESR spectroscopy to investigate the magnetic anisotropy effects in a spin-1/2 Heisenberg ladder compound, revealing the role of Dzyaloshinskii-Moriya interactions in low-temperature linewidth behavior.

Contribution

It provides the first analysis of ESR linewidth temperature dependence in a strong-rung ladder, highlighting the influence of magnetic anisotropy and Dzyaloshinskii-Moriya interactions.

Findings

ESR linewidth behavior is governed by magnetic anisotropy.

Uniform Dzyaloshinskii-Moriya interaction influences ESR linewidth.

Low-temperature ESR linewidth behavior is explained by anisotropic interactions.

Abstract

Cu(C$_8$H$_6$N$_2$)Cl$_2$, a strong-rung spin-1/2 Heisenberg ladder compound, is probed by means of electron spin resonance (ESR) spectroscopy in the field-induced gapless phase above $H_{c1}$. The temperature dependence of the ESR linewidth is analyzed in the quantum field theory framework, suggesting that the anisotropy of magnetic interactions plays a crucial role, determining the peculiar low-temperature ESR linewidth behavior. In particular, it is argued that the uniform Dzyaloshinskii-Moriya interaction (which is allowed on the bonds along the ladder legs) can be the source of this behavior in Cu(C$_8$H$_6$N$_2$)Cl$_2$.