Spatial Structure of Spin Polarons in the t-J Model

TL;DR

This paper investigates how a spin polaron distorts the antiferromagnetic background in the t-J model using a slave fermion approach, revealing persistent correlations and dipolar distortions influenced by quasiparticle momentum.

Contribution

It introduces a selfconsistent Born approximation method to analyze spin correlations around a moving hole in the t-J model, showing detailed spatial and momentum-dependent structures.

Findings

Antiferromagnetic correlations near the hole are reduced but persist at small J.

Spin structure exhibits dipolar distortions sensitive to quasiparticle momentum.

Spectral weight of quasiparticles remains finite despite distortions.

Abstract

The deformation of the quantum Neel state induced by a spin polaron is analyzed in a slave fermion approach. Our method is based on the selfconsistent Born approximation for Green's and the wave function for the quasiparticle. The results of various spin-correlation functions relative to the position of the moving hole are discussed and shown to agree with those available from small cluster calculations. Antiferromagnetic correlations in the direct neighborhood of the hole are reduced, but they remain antiferromagnetic even for J as small as 0.1 t. These correlation functions exhibit dipolar distortions in the spin structure, which sensitively depend on the momentum of the quasiparticle. Their asymptotic decay with the distance from the hole is governed by power laws, yet the spectral weight of the quasiparticles does not vanish.