Finding the Rashba-type spin-splitting from interband scattering in quasiparticle interference maps

TL;DR

This study uses quasiparticle interference mapping via STM to identify multiple scattering vectors in a Rashba system, enabling precise band structure determination including spin splitting.

Contribution

It introduces a method to extract detailed band dispersions and Rashba splitting from interband scattering in quasiparticle interference maps, expanding analysis capabilities for spin-orbit coupled surfaces.

Findings

Multiple scattering vectors identified in QPI maps.

Quantitative band dispersion including Rashba splitting obtained.

Results agree with ARPES data.

Abstract

We have studied the BiCu$_2$/Cu(111) surface alloy using low-temperature scanning tunneling microscopy and spectroscopy. We observed standing waves caused by scattering off defects and step edges. Different from previous studies on similar Rashba-type surfaces, we identified multiple scattering vectors that originate from various intraband as well as interband scattering processes. A detailed energy-dependent analysis of the standing-wave patterns enables a quantitative determination of band dispersions, including the Rashba splitting. The results are in good agreement with ARPES data and demonstrate the usefulness of this strategy to determine the band structure of Rashba systems. The lack of other possible scattering channels will be discussed in terms of spin conservation and hybridization effects. The results open new possibilities to study spin-dependent scattering on complex spin-orbit coupled surfaces.