Finite f-Electron Bandwidth in a Heavy Fermion Model

TL;DR

This study uses determinant quantum Monte Carlo to explore how non-zero f-electron hopping affects the magnetic and electronic properties of the two-dimensional periodic Anderson model, revealing persistent band insulator-metal behavior and altered spin correlations.

Contribution

It demonstrates the impact of finite f-electron hopping on magnetic correlations and Kondo screening in the 2D periodic Anderson model, extending understanding beyond the t_f=0 case.

Findings

Remnant of insulator-metal line persists with finite t_f.

Maximal antiferromagnetic correlations occur near specific t_f values.

Finite t_f alters the development of short-range and long-range spin correlations.

Abstract

Determinant Quantum Monte Carlo (DQMC) is used to study the effect of non-zero hopping t_f in the localized f-band of the periodic Anderson model (PAM) in two dimensions. The low temperature properties are determined in the plane of interband hybridization V and t_f at fixed U_f and half-filling, including the case when the sign of t_f is opposite to that of the conduction band t_d. For t_f and t_d of the same sign, and when t_f=t_d > (V =4_td)^2, the non-interacting system is metallic. We show that a remnant of the band insulator to metal line at U_f = 0 persists in the interacting system, manifesting itself as a maximal tendency toward antiferromagnetic correlations at low temperature. In this optimal t_f region, short range (e.g. near-neighbor) and long-range spin correlations develop at similar temperatures and have comparable magnitude. Both observations are in stark contrast with the situation in the widely studied PAM (t_f = 0) and single band Hubbard model, where short range correlations are stronger and develop at higher temperature. The effect that finite t_f has on Kondo screening is investigated by considering the evolution of the local density of states for selected t_f as a function of V . We use mean field theory as a tool to discriminate those aspects of the physics that are genuinely many-body in character.