Localized excitation in the hybridization gap in YbAl3

TL;DR

This study uses inelastic neutron scattering to reveal a localized magnetic excitation within the hybridization gap of YbAl3 at low temperatures, indicating novel localized states in this intermediate valence compound.

Contribution

It demonstrates the existence of a localized magnetic excitation in the hybridization gap of YbAl3, a novel observation in this class of materials.

Findings

Identification of a localized excitation at ~33meV in YbAl3

Differentiation of scattering behavior near E1 and E2 energies

Evidence of localized states within the hybridization gap

Abstract

The intermediate valence compound YbAl3 exhibits a broad magnetic excitation with characteristic energy E1 ~ 50meV, of order of the Kondo energy (TK ~ 600-700K). In the low temperature (T < Tcoh ~ 40K) Fermi liquid state, however, a new magnetic excitation arises at E2 ~ 33meV, which lies in the hybridization gap that exists in this compound. We show, using inelastic neutron scattering on a single-crystal sample, that while the scattering at energies near E1 has the momentum (Q-) dependence expected for interband scattering across the indirect gap, the scattering near E2 is independent of Q. This suggests that it arises from a spatially-localized excitation in the hybridization gap.