Hubbard model on an anisotropic checkerboard lattice at finite temperatures: Magnetic and metal–insulator transitions

Abstract

We study magnetic and Mott transitions of the Hubbard model on the geometrically frustrated anisotropic checkerboard lattice at half filling using cellular dynamical mean-field theory. Phase diagrams over a wide area of the parameter space are obtained by varying the interparticle interaction strength, geometric frustration strength, and temperature. Our results show that frustration and thermal fluctuations play a competing role against the interactions and in general favor a metallic phase without antiferromagnetic order. Due to their interplay, the system exhibits competition between antiferromagnetic insulator, antiferromagnetic metal, paramagnetic insulator, and paramagnetic metal phases in the intermediate-interaction regime. In the strong-interaction limit, which reduces to the Heisenberg model, our result is consistent with previous studies.