# Fast optical control of spin in semiconductor interfacial structures

## TL;DR

This paper demonstrates a picosecond optical method to rapidly control and reset spin polarization in GaAs/AlGaAs interfaces, enabling high-speed spin transport for potential spintronic applications.

## Contribution

It introduces a modified resonant spin amplification technique to distinguish spin populations and shows how to optically control spin density by modulating electrostatic confinement.

## Key findings

- Spin polarization can be optically removed within picoseconds.
- Spin density is controllable via electrostatic confinement adjustments.
- Confinement disturbance recovers in hundreds of picoseconds.

## Abstract

We report on a picosecond-fast optical removal of spin polarization from a self-confined photo-carrier system at an undoped GaAs/AlGaAs interface possessing superior long-range and high-speed spin transport properties. We employed a modified resonant spin amplification technique with unequal intensities of subsequent pump pulses to experimentally distinguish the evolution of spin populations originating from different excitation laser pulses. We demonstrate that the density of spins, which is injected into the system by means of the optical orientation, can be controlled by reducing the electrostatic confinement of the system using an additional generation of photocarriers. It is also shown that the disturbed confinement recovers within hundreds of picoseconds after which spins can be again photo-injected into the system.