Magnetic Excitation of t-J Model with Quasi-One-Dimensional Fermi Surface -- Possible Relevance to LSCO Systems

TL;DR

This paper models magnetic excitations in LSCO systems using a quasi-one-dimensional Fermi surface within the t-J model, revealing persistent incommensurate peaks unaffected by the d-wave gap, aligning with experimental observations.

Contribution

It introduces a quasi-one-dimensional Fermi surface model for LSCO and calculates the spin excitation spectrum, highlighting features consistent with experimental magnetic excitations.

Findings

Incommensurate and diagonal incommensurate peaks are present in the spin excitation spectrum.

Peaks are robust and persist at low doping levels, unaffected by the d-wave gap.

The results support the q-1d Fermi surface picture as a key to understanding LSCO magnetic excitations.

Abstract

On the basis of the picture of a quasi-one-dimensional (q-1d) Fermi surface (FS), recently proposed by authors for LSCO systems, spin excitation spectrum, Im chi(q,omega), is calculated in the 'RPA' within the slave-boson mean-field approximation to the t-J model. It is found that Im chi(q,omega) shows both incommensurate (IC) and diagonal IC (DIC) peaks, whose realization does not depend on the existence of the d-wave gap. The peak positions do not change appreciably with omega and the sharp peaks survive down to the low hole doping rate. The d-wave gap suppresses both the IC peak and the DIC peak, but the degree of suppression as a function of omega is different between them. Taking these results together with results for the two-dimensional FS, we argue that essential features of magnetic excitation in LSCO systems can be understood in terms of the q-1d picture of the FS.