Meson formation in mixed-dimensional t-J models

TL;DR

This paper investigates meson formation in a mixed-dimensional t-J model, revealing bound states of holons and spinons connected by spin strings, with implications for understanding charge carriers in doped Mott insulators.

Contribution

It introduces a simplified mixed-dimensional t-J model and provides evidence for mesonic bound states of holons and spinons, advancing understanding of spin-charge separation.

Findings

Evidence for mesonic bound states of holons and spinons.

Prediction of short-range hidden string order.

Potential for experimental verification with ultracold atoms.

Abstract

Surprising properties of doped Mott insulators are at the heart of many quantum materials, including transition metal oxides and organic materials. The key to unraveling complex phenomena observed in these systems lies in understanding the interplay of spin and charge degrees of freedom. One of the most debated questions concerns the nature of charge carriers in a background of fluctuating spins. To shed new light on this problem, we suggest a simplified model with mixed dimensionality, where holes move through a Mott insulator unidirectionally while spin exchange interactions are two dimensional. By studying individual holes in this system, we find direct evidence for the formation of mesonic bound states of holons and spinons, connected by a string of displaced spins -- a precursor of the spin-charge separation obtained in the 1D limit of the model. Our predictions can be tested using ultracold atoms in a quantum gas microscope, allowing to directly image spinons and holons, and reveal the short-range hidden string order which we predict in this model.