High-spin polaron in lightly doped CuO$_2$ planes

TL;DR

This paper introduces a detailed spin polaron model for lightly doped CuO$_2$ layers, revealing new low-energy states with high total spin and emphasizing the role of spin fluctuations in the system's physics.

Contribution

It presents a minimal yet detailed spin polaron model and uses exact diagonalization to uncover novel high-spin polaron states overlooked in previous studies.

Findings

Spin-polaron states with total spin 3/2 are lowest in certain Brillouin zone regions.

Quasiparticle weight is zero in some regions, indicating orthogonal states.

Highlights importance of spin fluctuation treatment in many-body systems.

Abstract

We device and investigate numerically a minimal yet detailed spin polaron model that describes lightly doped CuO$_2$ layers. The low-energy physics of a hole is studied by total-spin-resolved exact diagonalization on clusters of up to 32 CuO$_2$ unit cells, revealing features missed by previous studies. In particular, spin-polaron states with total spin 3/2 are the lowest eigenstates in several regions of the Brillouin zone. In these regions, and also at other points the quasiparticle weight is identically zero, indicating orthogonal states to those represented in the one electron Green's function. This highlights the importance of proper treatment of spin fluctuations in the many-body background.