# Direct Mapping of Spin and Orbital Entangled Wavefunction under Interband Spin-Orbit coupling of Rashba Spin-Split Surface States

## TL;DR

This study employs spin- and angle-resolved photoemission spectroscopy to directly map and analyze the complex spin-orbital entanglement in Rashba surface states caused by interband spin-orbit coupling, revealing deviations from the standard Rashba model.

## Contribution

It provides the first direct experimental imaging of the modified spin and orbital characters in Rashba states due to interband spin-orbit hybridization.

## Key findings

- Interband spin-orbit coupling alters spin and orbital characters.
- Hybridization leads to enriched spin-orbital entanglement.
- Experimental results match first-principles calculations.

## Abstract

We use spin- and angle-resolved photoemission spectroscopy (SARPES) combined with polarization-variable laser and investigate the spin-orbit coupling effect under interband hybridization of Rashba spin-split states for the surface alloys Bi/Ag(111) and Bi/Cu(111). In addition to the conventional band mapping of photoemission for Rashba spin-splitting, the different orbital and spin parts of the surface wavefucntion are directly imaged into energy-momentum space. It is unambiguously revealed that the interband spin-orbit coupling modifies the spin and orbital character of the Rashba surface states leading to the enriched spin-orbital entanglement and the pronounced momentum dependence of the spin-polarization. The hybridization thus strongly deviates the spin and orbital characters from the standard Rashba model. The complex spin texture under interband spin-orbit hybridyzation proposed by first-principles calculation is experimentally unraveled by SARPES with a combination of p- and s-polarized light.