LiV2O4: Hund-Assisted Orbital-Selective Mottness

TL;DR

This paper demonstrates that the heavy fermion behavior and low coherence scale in LiV₂O₄ originate from proximity to a Hund-assisted orbital-selective Mott state, revealed through advanced ab initio dynamical mean-field calculations.

Contribution

It introduces a detailed ab initio dynamical mean-field study showing Hund coupling's role in orbital rearrangement and heavy mass formation in LiV₂O₄, highlighting the orbital-selective Mott physics.

Findings

Hund coupling crucial for orbital population rearrangement

Heavy effective mass (~100 times electron mass) explained by correlations

Coherence scale estimated at 1-2 Kelvin

Abstract

We show that the remarkably small Fermi-liquid coherence scale and large effective mass observed in LiV$_2$O$_4$ are due to the proximity of a Hund-assisted orbital-selective Mott state. Our work is based on an ab initio dynamical mean-field approach, combining several quantum impurity solvers to capture the physics from high to very low temperature. We find that the Hund coupling plays a crucial role in rearranging the orbital populations and in generating the heavy mass and low coherence scale. The latter is found to be approximately 1-2 Kelvin, even though the most correlated orbital is found to be significantly doped ~10% away from half-filling. A flat quasiparticle band appears near the Fermi level as a result of the strong electronic correlations. Finally, we discuss our results in comparison to experiments.