Universal Magnetic Properties of $La_{2-\delta} Sr_{\delta} Cu O_4$ at Intermediate Temperatures

TL;DR

This paper develops a universal theory for magnetic properties of La2−δSrδCuO4 at intermediate temperatures, matching experimental data and simulations through a scaling approach for susceptibility, correlation length, and NMR relaxation rate.

Contribution

It introduces a universal scaling framework for 2D quantum antiferromagnets applicable at various temperature regimes, validated by experiments and simulations.

Findings

Universal scaling forms for susceptibility, correlation length, and NMR rate.

Quantitative agreement with experimental data on La2−δSrδCuO4.

Asymptotic behaviors of magnetic properties at high temperature ratios.

Abstract

We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature ($T$) stiffness $\rho_s$, but with the ratio $k_B T / \rho_s $ arbitrary. Universal scaling forms for the uniform susceptibility ($\chi_u$), correlation length($\xi$), and NMR relaxation rate ($1/T_1$) are proposed and computed in a $1/N$ expansion and by Mont\'{e}-Carlo simulations. For large $k_B T/\rho_s$, $\chi_u (T)/T$ and $T\xi(T)$ asymptote to universal values, while $1/T_{1}(T)$ is nearly $T$-independent. We find good quantitative agreement with experiments and some numerical studies on $La_{2-\delta} Sr_{\delta} Cu O_4$.