63Cu NQR evidence of dimensional crossover to anisotropic 2d regime in S= 1/2 three-leg ladder Sr2Cu3O5

TL;DR

This study uses 63Cu NQR to investigate spin correlations in Sr2Cu3O5, revealing a dimensional crossover from 1D to anisotropic 2D behavior below 300 K, confirming theoretical models of spin dynamics.

Contribution

First experimental verification of the renormalized classical behavior of the anisotropic non-linear sigma model in a 2D spin system.

Findings

Dimensional crossover occurs below 300 K.

Spin-spin correlation length transitions from ~1/T to exponential behavior.

Supports theoretical models of anisotropic 2D spin dynamics.

Abstract

We probed spin-spin correlations up to 725 K with 63Cu NQR in the S= 1/2 three-leg ladder Sr2Cu3O5. We present experimental evidence that below 300 K, weak inter-ladder coupling causes dimensional crossover of the spin-spin correlation length \xi from quasi-1d (\xi ~ 1/T) to anisotropic 2d regime (\xi \~ exp[2\pi\rho_{s}/T], where 2\pi\rho_{s} = 290 +/- 30 K is the effective spin stiffness). This is the first experimental verification of the renormalized classical behavior of the anisotropic non-linear sigma model in 2d, which has been recently proposed for the striped phase in high T_{c} cuprates.