Single hole dynamics in dimerized spin liquids

TL;DR

This paper investigates the behavior of a single hole in dimerized spin liquids, revealing a crossover from quasiparticles with spin 1/2 to higher spins in a spin ladder, and a vanishing quasiparticle residue near antiferromagnetic instability in coupled planes.

Contribution

It provides a detailed analysis of single hole dynamics in two different dimerized spin liquid systems, highlighting the spin crossover and the critical behavior near magnetic instability.

Findings

Quasiparticle residue remains close to unity in the spin ladder at small t/J.

Higher spin bound states emerge at large t/J in the ladder.

Quasiparticle residue vanishes at the antiferromagnetic instability in coupled planes.

Abstract

The dynamics of a single hole in quantum antiferromagnets is influenced by magnetic fluctuations. In the present work we consider two situations. The first one corresponds to a single hole in the two leg t-J spin ladder. In this case the wave function renormalization is relatively small and the quasiparticle residue of the S=1/2 state remains close to unity. However at large t/J there are higher spin (S=3/2,5/2,..) bound states of the hole with the magnetic excitations, and therefore there is a crossover from quasiparticles with S=1/2 to quasiparticles with higher spin. The second situation corresponds to a single hole in two coupled antiferromagnetic planes very close to the point of antiferromagnetic instability. In this case the hole wave function renormalization is very strong and the quasiparticle residue vanishes at the point of instability.