Ab initio study on heavy-fermion behavior in LiV$_2$O$_4$: Role of Hund's coupling and stability

TL;DR

This study uses advanced ab initio methods to analyze the heavy-fermion behavior in LiV$_2$O$_4$, highlighting the role of Hund's coupling and phase stability, and revealing its position between orbital-selective Mott phases.

Contribution

It provides a detailed ab initio analysis of LiV$_2$O$_4$, demonstrating its placement between Mott phases and elucidating the influence of Hund's coupling on its heavy fermion behavior.

Findings

LiV$_2$O$_4$ is between two orbital-selective Mott phases.

Emergence of a sharp quasi-particle peak above the Fermi level.

LiV$_2$O$_4$ exhibits robust Hund's metal behavior.

Abstract

LiV$_2$O$_4$ is a member of the so-called $3d$ heavy fermion compounds, with effective electron mass exceeding 60 times the free electron mass, comparable to $4f$ heavy fermion compounds. The origin of the strong electron correlation in combination with its metallic character have been a subject of intense theoretical and experimental discussion, with Kondo-like physics and Mott-physics being suggested as its physical origin. Here we report state-of-the art \textit{ab initio} Density Functional Theory + dynamical mean-field theory calculations for LiV$_2$O$_4$ for the full three orbital V $t_\mathrm{2g}$ manifold, and present temperature-dependent spectral properties. We map out the phase diagram for a representative 3-orbital model system as a function of doping and interaction strength, which indicates that LiV$_2$O$_4$ is located between two orbital-selective Mott phases, giving rise to a robust strongly correlated Hund's metal behavior. At low temperature we find the emergence of a strongly renormalized sharp quasi-particle peak a few meV above the Fermi level of V $a_\mathrm{1g}$ character, in agreement with experimental reports.