Chiral spin liquid state of strongly interacting bosons with a moat dispersion: a Monte Carlo simulation

Abstract

We consider a system of strongly interacting bosons in two dimensions with moat band dispersion which supports an infinitely degenerate energy minimum along a closed contour in the Brillouin zone. The system has been theoretically predicted to stabilize a chiral spin liquid (CSL) ground state. In the thermodynamic limit and vanishing densities, $n\rightarrow 0$, chemical potential, $μ$, of the uniform CSL state was shown to scale with $n$ as $μ\sim n^2\log ^2n$. Here we perform a Monte Carlo simulation to find the parametric window for particle density, $n \lesssim \frac{k^2_0}{82 π}$, where $k_0$ is the linear size of the moat (the radius for a circular moat), for which the scaling $\sim n^2\log ^2n$ in the equation of state of the homogeneous CSL is preserved. We variationally show that the uniform CSL state is favorable in an interval beyond the obtained scale and present a schematic phase diagram for the system. Our results offer some density estimates for observing the low-density behavior of CSL in time-of-flight experiments with a recently Floquet-engineered moat band system of ultracold atoms in Phys. Rev. Lett. 128, 213401 (2022), and for the recent experiments on emergent excitonic topological order in imbalanced electron-hole bilayers.