# Spin-orbit scattering visualized in quasiparticle interference

## TL;DR

This study demonstrates that spin-orbit scattering significantly influences quasiparticle interference patterns, and introduces a method to detect it using spectroscopic-imaging STM, supported by numerical simulations on BiTeI.

## Contribution

The paper presents a novel approach to visualize spin-orbit scattering in QPI patterns and extends simulation techniques to include spin-orbit effects.

## Key findings

- Spin-orbit scattering affects QPI patterns in BiTeI.
- Numerical simulations accurately reproduce experimental QPI data.
- A selection rule makes spin-orbit scattering detectable in QPI patterns.

## Abstract

In the presence of spin-orbit coupling, electron scattering off impurities depends on both spin and orbital angular momentum of electrons -- spin-orbit scattering. Although some transport properties are subject to spin-orbit scattering, experimental techniques directly accessible to this effect are limited. Here we show that a signature of spin-orbit scattering manifests itself in quasiparticle interference (QPI) imaged by spectroscopic-imaging scanning tunneling microscopy. The experimental data of a polar semiconductor BiTeI are well reproduced by numerical simulations with the $T$-matrix formalism that include not only scalar scattering normally adopted but also spin-orbit scattering stronger than scalar scattering. To accelerate the simulations, we extend the standard efficient method of QPI calculation for momentum-independent scattering to be applicable even for spin-orbit scattering. We further identify a selection rule that makes spin-orbit scattering visible in the QPI pattern. These results demonstrate that spin-orbit scattering can exert predominant influence on QPI patterns and thus suggest that QPI measurement is available to detect spin-orbit scattering.