Hole motion in an arbitrary spin background: Beyond the minimal spin-polaron approximation

TL;DR

This paper investigates the motion of a single hole in 2D magnetic backgrounds within the t-J model, introducing a generalized string approach to describe spin polarons beyond minimal approximations, revealing momentum-dependent spectral features.

Contribution

It develops a generalized string picture for spin polarons in the 2D t-J model, extending beyond minimal size approximations and interpolating between ordered and disordered magnetic backgrounds.

Findings

Reproduces known quasiparticle band in antiferromagnetic background

Spectral function shape varies strongly with momentum in disordered background

Quasiparticle weight vanishes across all momenta in disordered case

Abstract

The motion of a single hole in an arbitrary magnetic background is investigated for the 2D t-J model. The wavefunction of the hole is described within a generalized string picture which leads to a modified concept of spin polarons. We calculate the one-hole spectral function using a large string basis for the limits of a Neel ordered and a completely disordered background. In addition we use a simple approximation to interpolate between these cases. For the antiferromagnetic background we reproduce the well-known quasiparticle band. In the disordered case the shape of the spectral function is found to be strongly momentum-dependent, the quasiparticle weight vanishes for all hole momenta. Finally, we discuss the relevance of results for the lowest energy eigenvalue and its dispersion obtained from calculations using a polaron of minimal size as found in the literature.