Mott transition in the Hubbard model on the hyper-kagome lattice

Abstract

Motivated by recent experiment on the Na$_4$Ir$_3$O$_8$ compound we study the Hubbard model on the "hyper-kagome lattice", which forms a three-dimensional network of corner sharing triangles, using dynamical cluster approximation (DCA) method with $N_c$=12 combined with the continuous-time quantum Monte Carlo (CT QMC) method. The system undergoes a Mott transition if the Hubbard interaction $U/W$ ($W$ is the bandwidth) exceeds the value of 1.2 for $T$=0.1 and displays reentrant behavior due to competition between the magnetic correlation and the kinetic energy of electrons due to the geometrical frustration. We observe a "critical slowing down" of the double occupancy which shows evidence of a continuous transition. The nearest-neighbor and next nearest-neighbor spin-spin correlations indicate a paramagnetic metallic state in the weak-coupling regime and an antiferromagnetic (AF) Mott insulator in the strong-coupling regime within the temperature range which we can access with our numerical tools.