Z2 parton phases in the mixed-dimensional $t-J_z$ model

TL;DR

This paper explores the phase diagram of a mixed-dimensional $t-J_z$ model, revealing stripe, confined meson-gas, and deconfined chargon-gas phases, with potential experimental realization in ultracold atom systems.

Contribution

It introduces a Z2 lattice gauge theory framework for the $t-J_z$ model and confirms phase behavior through quantum Monte Carlo simulations.

Findings

Identification of stripe phase at low temperatures

Discovery of deconfined chargon-gas phase at high doping

Critical temperature for stripe formation near the spin-exchange energy $J_z$

Abstract

We study the interplay of spin- and charge degrees of freedom in a doped Ising antiferromagnet, where the motion of charges is restricted to one dimension. The phase diagram of this mixed-dimensional $t - J_z$ model can be understood in terms of spin-less chargons coupled to a Z2 lattice gauge field. The antiferromagnetic couplings give rise to interactions between Z2 electric field lines which, in turn, lead to a robust stripe phase at low temperatures. At higher temperatures, a confined meson-gas phase is found for low doping whereas at higher doping values, a robust deconfined chargon-gas phase is seen which features hidden antiferromagnetic order. We confirm these phases in quantum Monte Carlo simulations. Our model can be implemented and its phases detected with existing technology in ultracold atom experiments. The critical temperature for stripe formation with a sufficiently high hole concentration is around the spin-exchange energy $J_z$, i.e., well within reach of current experiments.