Spatial interferences in the electron transport of heavy fermion materials

TL;DR

This paper investigates how spatial interference affects electron transport in heavy fermion materials, revealing limitations of point contact spectroscopy in probing f-electron spectral features due to interference effects.

Contribution

It provides a microscopic analysis of spatial interference effects on electron transport in heavy fermion systems using nonequilibrium Green's functions, highlighting their impact on spectroscopic measurements.

Findings

Spatial interference causes a weighted average in momentum space affecting conductance.

Interference can suppress band features like the hybridization gap.

Point contact spectroscopy may be intrinsically inefficient for probing f-electrons.

Abstract

The scanning tunneling microscopy/spectroscopy and the point contact spectroscopy represent one of the major progresses in recent heavy fermion research. Both have revealed important information on the composite nature of the emergent heavy electron quasiparticles. However, a detailed and thorough microscopic understanding of the similarities and differences in the underlying physical processes of these techniques is still lacking. Here we study the electron transport in the normal state of the periodic Anderson lattice by using the Keldysh nonequilibrium Green's function technique. In addition to the well-known Fano interference between the conduction and f-electron channels, our results further reveal the effect of spatial interference between different spatial paths at the interface on the differential conductance and their interesting interplay with the band features such as the hybridization gap and the Van Hove singularity. We find that the spatial interference leads to a weighted average in the momentum space for the electron transport and could cause suppression of the electronic band features under certain circumstances. In particular, it reduces the capability of probing the f-electron spectral weight near the edges of the hybridization gap for large interface depending on the Fermi surface of the lead. Our results indicates an intrinsic inefficiency of the point contact spectroscopy in probing the f-electrons.