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Finite-Temperature Phase Diagram of Hard-Core Bosons in Two Dimensions

Guido Schmid·Synge Todo·Matthias Troyer·Ansgar Dorneich
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Abstract

We determine the finite-temperature phase diagram of the square lattice hard-core boson Hubbard model with nearest neighbor repulsion using quantum Monte Carlo simulations. This model is equivalent to an anisotropic spin-1/2 XXZ model in a magnetic field. We present the rich phase diagram with a first order transition between solid and superfluid phase, instead of a previously conjectured supersolid and a tricritical end point to phase separation. Unusual reentrant behavior with ordering upon increasing the temperature is found, similar to the Pomeranchuk effect in 3He.

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Guido Schmid, Synge Todo, Matthias Troyer, Ansgar Dorneich. 2002-02-15. Finite-Temperature Phase Diagram of Hard-Core Bosons in Two Dimensions. https://doi.org/10.1103/physrevlett.88.167208

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