Evidence for direct and indirect gap in FeSi from electron tunneling spectroscopy

TL;DR

This study uses electron tunneling spectroscopy to distinguish between the direct and indirect energy gaps in FeSi, revealing different electronic states depending on the tunneling configuration.

Contribution

It demonstrates how different tunneling setups selectively probe the direct or indirect gap in FeSi, providing new spectroscopic insights.

Findings

Pt-Rh tip tunneling is sensitive to the indirect gap and d-partial density of states.

FeSi-FeSi junctions reveal the direct gap and c-partial density of states.

Distinct tunneling configurations probe different electronic features in FeSi.

Abstract

We report electron tunneling spectroscopy studies on single crystalline FeSi sample performed for the case of homogeneous tunnel junction contacts and for the case of counter electrodes made from Pt-Rh alloy. Our results reveal that while the tunneling spectroscopy in the configuration with Pt-Rh tip is preferably sensitive to the d-partial density of states and to the indirect energy gap, the FeSi-FeSi type of tunnel junction yields spectroscopic information on the c-partial density of states and on the direct gap in FeSi.