# Photoinduced Rashba spin to charge conversion via interfacial unoccupied state

## TL;DR

This paper demonstrates efficient photoinduced spin to charge conversion at an interface via Rashba spin splitting in an unoccupied state, enabling light energy harvesting without magnetic materials or external fields.

## Contribution

It provides the first evidence of spin-charge conversion through Rashba splitting in unoccupied states above the Fermi level at a specific interface.

## Key findings

- Rashba coefficient of 1.72×10^{-10} eV·m predicted at 1.98 eV above Fermi level.
- Helicity-dependent spin to charge conversion observed at 1.96 eV.
- Spin current generation of 10^6 A/m^2 measured at room temperature.

## Abstract

At interfaces with inversion symmetry breaking, Rashba effect couples the motion of electrons to their spin; as a result, spin-charge interconversion mechanism can occur. These interconversion mechanisms commonly exploit Rashba spin splitting at the Fermi level by spin pumping or spin torque ferromagnetic resonance. Here, we report evidence of significant photoinduced spin to charge conversion via Rashba spin splitting in an unoccupied state above the Fermi level at the Cu(111)/$\alpha$-Bi$_{2}$O$_{3}$ interface. We predict an average Rashba coefficient of $1.72\times 10^{-10}eV.m$ at 1.98 eV above the Fermi level, by fully relativistic first-principles analysis of the interfacial electronic structure with spin orbit interaction. We find agreement with our observation of helicity dependent photoinduced spin to charge conversion excited at 1.96 eV at room temperature, with spin current generation of $J_{s}=10^{6}A/m^{2}$. The present letter shows evidence of efficient spin-charge conversion exploiting Rashba spin splitting at excited states, harvesting light energy without magnetic materials or external magnetic fields.