Crossover to non-Fermi-liquid spin dynamics in cuprates

TL;DR

This paper investigates the transition from Fermi-liquid to non-Fermi-liquid spin dynamics in cuprates using numerical models, revealing a doping-dependent crossover characterized by a low energy scale in underdoped regimes.

Contribution

It provides a quantitative analysis of spin correlations and susceptibility in cuprates, identifying a doping-dependent crossover in spin dynamics.

Findings

Low energy scale $\omega_{FL}$ in underdoped cuprates

Steep increase of $\omega_{FL}$ in overdoped regime

Smooth crossover between Fermi-liquid and non-Fermi-liquid behavior

Abstract

The antiferromagnetic spin correlation function $S_{\bf Q}$, the staggered spin susceptibility $\chi_{\bf Q}$ and the energy scale $\omega_{FL}=S_{\bf Q}/\chi_{\bf Q}$ are studied numerically within the t-J model and the Hubbard model, as relevant to cuprates. It is shown that $\omega_{FL}$, related to the onset of the non-Fermi-liquid spin response at $T>\omega_{FL}$, is very low in the regime below the 'optimum' hole doping $c_h < c_h^* \sim 0.16$, while it shows a steep increase in the overdoped regime. A quantitative analysis of NMR spin-spin relaxation-rate $1/T_{2G}$ for various cuprates reveals a similar behavior, indicating on a sharp, but continuous, crossover between a Fermi-liquid and a non-Fermi-liquid behavior as a function of doping.