Cluster dynamical mean-field study of the Hubbard model on a 3D frustrated hyperkagome lattice

TL;DR

This study uses cluster dynamical mean-field theory to analyze the Hubbard model on a frustrated hyperkagome lattice, revealing temperature-dependent electronic properties and their relation to strong correlations and unique electronic structures.

Contribution

It provides the first detailed analysis of the Hubbard model on a hyperkagome lattice using cluster DMFT, highlighting the effects of strong correlations on thermodynamic and dynamic properties.

Findings

Peak in specific heat at T_{p1} decreases with stronger correlations.

Spin-lattice relaxation rate peaks at T_{p2} and follows Korringa law at low T.

Electronic structure features like pseudo-gap, van Hove singularity, and flat band influence behaviors.

Abstract

We study the Hubbard model on a geometrically-frustrated hyperkagome lattice by a cluster extension of the dynamical mean field theory. We calculate the temperature ($T$) dependences of the specific heat ($C$) and the spin-lattice relaxation time ($T_1$) in correlated metallic region. $C/T$ shows a peak at $T=T_{p1}$ and rapidly decreases as $T->0$. On the other hand, $1/T_1T$ has a peak at a higher temperature $T_{p2}$ than $T_{p1}$, and largely decreases below $T_{p2}$, followed by the Korringa law $1/T_1 propto T$ as $T->0$. Both peak temperatures are suppressed and the peaks become sharper as electron correlation is increased. These behaviors originate from strong renormalization of the energy scales in the peculiar electronic structure in this frustrated system; a pseudo-gap like feature, the van-Hove singularity, and the flat band. The results are discussed in comparison with the experimental data in the hyperkagome material, Na$_4$Ir$_3$O$_8$.