Finite-temperature ferromagnetic correlations in the Kagome lattice Fermi-Hubbard model

Despite being well known for its strong anti-ferromagnetic correlations, under the right conditions, the Fermi-Hubbard model can also host ferromagnetism. Here, we explore the model on the Kagome lattice, which due to the presence of a flat non-interacting band, is proven to host ferromagnetism at a certain density range in the ground state. Yet, the extent of correlations at finite temperatures has not been systematically studied. We study short-range spin correlations and other thermodynamic properties using quantum Monte Carlo simulations and the numerical linked-cluster expansions and identify the regions with dominant ferromagnetic correlations as the temperature and interaction strength are varied.