Quasiparticle Interference Studies of Quantum Materials

TL;DR

This review discusses how quasiparticle interference imaging, combined with STM and ab initio calculations, advances understanding of electronic properties in topological and quantum materials, revealing surface states, phase coherence, and wave function structures.

Contribution

It provides a comprehensive overview of how quasiparticle interference techniques probe fundamental electronic properties in various quantum materials, highlighting recent experimental insights.

Findings

Mesoscopic size quantization and phase coherence in nanowires

Helical spin protection and fluctuations in topological insulators

Wave function structure and surface potential insensitivity in Weyl semimetals

Abstract

Exotic electronic states are realized in novel quantum materials. This field is revolutionized by the topological classification of materials. Such compounds necessarily host unique states on their boundaries. Scanning tunneling microscopy studies of these surface states have provided a wealth of spectroscopic characterization, with the successful cooperation of ab initio calculations. The method of quasiparticle interference imaging proves to be particularly useful for probing the dispersion relation of the surface bands. Herein, how a variety of additional fundamental electronic properties can be probed via this method is reviewed. It is demonstrated how quasiparticle interference measurements entail mesoscopic size quantization and the electronic phase coherence in semiconducting nanowires; helical spin protection and energy-momentum fluctuations in a topological insulator; and the structure of the Bloch wave function and the relative insusceptibility of topological electronic states to surface potential in a topological Weyl semimetal.