Anomalously enhanced photoemission from the Dirac point and symmetry of the self-energy variations for the surface states in Bi2Se3

TL;DR

This paper investigates unusual photoemission features in Bi2Se3, revealing asymmetric spectral lines and enhanced emission at the Dirac point, linked to complex self-energy and interference effects.

Contribution

It uncovers the symmetry properties of the self-energy variations and explains the anomalous photoemission enhancements in Bi2Se3 surface states.

Findings

Spectral line asymmetry indicates specific scattering symmetry.

Enhanced photoemission at the Dirac point is likely due to final state interference.

Self-energy variations change sign across the Dirac point.

Abstract

Accurate analysis of the photoemission intensity from the surface states of Bi2Se3 reveals two unusual features: spectral line asymmetry and anomalously enhanced photoemission from the Dirac point. The former indicates a certain symmetry of a scattering process, which results in strongly k\omega-dependent contribution to the imaginary part of the self-energy that changes sign while crossing both the dispersion curves and the energy of the Dirac point. The latter is hard to describe by one particle spectral function while a final state interference seems to be plausible explanation.