Quasiparticle interference of C2-symmetric surface states in LaOFeAs parent compound

TL;DR

This study uses scanning tunneling microscopy to investigate surface states in LaOFeAs, revealing two-fold symmetric quasiparticle interference patterns that relate to nematic electronic structures in iron pnictides.

Contribution

First observation of quasiparticle interference patterns on LaOFeAs surfaces showing nematic symmetry, linking surface states to bulk electronic nematicity.

Findings

Detection of two types of atomically flat surfaces.

Observation of strong standing wave patterns due to quasiparticle interference.

Distribution of scattering wavevectors shows two-fold symmetry.

Abstract

We present scanning tunneling microscopy studies of the LaOFeAs parent compound of iron pnictide superconductors. Topographic imaging reveals two types of atomically flat surfaces, corresponding to the exposed LaO layer and FeAs layer respectively. On one type of surface, we observe strong standing wave patterns induced by quasiparticle interference of two-dimensional surface states. The distribution of scattering wavevectors exhibits pronounced two-fold symmetry, consistent with the nematic electronic structure found in the Ca(Fe1-xCox)2As2 parent state.