Absence of Hybridization Gap in Heavy Electron Systems and Analysis of YbAl3 in terms of Nearly Free Electron Conduction Band

TL;DR

This paper challenges the common assumption of a hybridization gap in heavy electron systems, demonstrating that YbAl3 can be accurately described by a nearly free electron model without such a gap, aligning well with experimental data.

Contribution

It introduces a simple effective band model for YbAl3 that omits the hybridization gap, providing a more accurate description of its electronic structure.

Findings

No hybridization gap in YbAl3 as shown by the model

Calculated properties match experimental results

Simplified model effectively describes heavy electron behavior

Abstract

In the analysis of the heavy electron systems, theoretical models with c-f hybridization gap are often used. We point out that such a gap does not exist and the simple picture with the hybridization gap is misleading in the metallic systems, and present a correct picture by explicitly constructing an effective band model of YbAl_3. Hamiltonian consists of a nearly free electron model for conduction bands which hybridize with localized f-electrons, and includes only a few parameters. Density of states, Sommerfeld coefficient, f-electron number and optical conductivity are calculated and compared with the band calculations and the experiments.