Magnetic States, Correlation Effects and Metal-Insulator Transition in FCC Lattice

TL;DR

This paper investigates the magnetic phase diagram and metal-insulator transition in the Hubbard model on an FCC lattice, emphasizing the role of electron correlations, hopping ratios, and magnetic ordering types.

Contribution

It provides a detailed analysis of the magnetic states and transition mechanisms in the FCC lattice Hubbard model using the slave-boson approach, highlighting the dominance of the Slater scenario.

Findings

MIT is first order for most t'/t ratios.

Insulator states are weakly correlated compared to metallic states.

Magnetic ordering varies with t'/t, including antiferromagnetic and spin-spiral states.

Abstract

The ground-state magnetic phase diagram (including collinear and spiral states) of the single-band Hubbard model for the face-centered cubic lattice and related metal-insulator transition (MIT) are investigated within the slave-boson approach by Kotliar and Ruckenstein. The correlation induced electronic spectrum narrowing and a comparison with a generalized Hartree-Fock approximation allow one to estimate the strength of correlation effects. This, as well as the MIT scenario, depends dramatically on the ratio of the next-nearest and nearest electron hopping integrals $t'/t$. In contrast with metallic state, possessing strong band narrowing, insulator one is only weakly correlated. The magnetic (Slater) scenario of MIT is found to be superior over the Mott one. Unlike simple and body-centered cubic lattices, MIT is the first order transition for most $t'/t$. The insulator state is type-II or type-III antiferromagnet, and the metallic state is spin-spiral, collinear antiferromagnet or paramagnet depending on $t'/t$. The picture of magnetic ordering is compared with that in the standard localized-electron (Heisenberg) model.