Thermodynamics of the XXZ shuriken lattice antiferromagnet

In this work, we study the thermodynamic phase diagram of the spin-1/2 XXZ model on the square-Kagome (or "shuriken") lattice, consisting of two sublattices (denoted "A" and "B") with inequivalent site couplings J_AA and J_AB and Ising anisotropy Δ. This model exhibits both magnetic and valence-bond solid (VBS) phases in the isotropic case, at large J_AA and J_AB respectively, as well as a highly frustrated intermediate regime that is thought to be a quantum spin liquid. We study thermodynamics and finite-temperature correlation functions of the two exchange-parameter XXZ model using exact diagonalization and the finite-temperature Lanczos method.