Electronic states and magnetic excitations in LiV2O4: Exact diagonalization study

TL;DR

This study uses exact diagonalization to analyze magnetic properties of LiV2O4, revealing how Hund's coupling influences ground states, excitations, and magnetic moments, aligning with recent neutron scattering experiments.

Contribution

It introduces a model combining localized spins and itinerant electrons with Hund's coupling, analyzed via exact diagonalization for the first time in this context.

Findings

Triplet states are favored by Hund's coupling.

Magnetic moments increase with temperature due to triplet population.

Results agree qualitatively with experimental neutron scattering data.

Abstract

Motivated by recent inelastic neutron scattering experiment we examine magnetic properties of LiV2O4. We consider a model which describes the half-filled localized A1g spins interacting via frustrated antiferromagnetic Heisenberg exchange and coupled by local Hund's interaction with the 1/8-filled itinerant Eg band, and study it within an exact diagonalization scheme. In the present study we limited the analysis to the case of the cluster of two isolated tetrahedrons. We obtained that both the ground state structure and low-lying excitations depend strongly on the value of the Hund's coupling which favors the triplet states. With increasing temperature the triplet states become more and more populated which results in the formation of non-zero residual magnetic moment. We present the temperature dependence of calculated magnetic moment and of the spin-spin correlation functions at different values of Hund's coupling and compare them with the experimental results.