Electrical Detection of Light Helicity using a Quantum Dots based Hybrid Device at Zero Magnetic Field

TL;DR

This study demonstrates a quantum dot-based device capable of detecting light helicity at zero magnetic field by leveraging magnetic anisotropy and spin relaxation properties, with potential applications in spintronics and quantum information.

Contribution

The paper introduces a novel hybrid device that detects photon helicity without external magnetic fields using quantum dots and magnetic electrodes, advancing spin-based photodetection technology.

Findings

Photocurrent asymmetry depends on light polarization and magnetic hysteresis.

Asymmetry amplitude decreases with temperature and can be tuned by bias.

Device operates as a multifunctional photodetector with insights into electron spin relaxation.

Abstract

Photon helicity-dependent photocurrent is measured at zero magnetic field on a device based on an ensemble of InGaAs/GaAs quantum dots that are embedded into a GaAs-based p-i-n diode. Our main goal is to take advantage of the long electron spin relaxation time expected in these nano-objects. In these experiments, no external magnetic field is required thanks to the use of an ultrathin magnetic CoFeB/MgO electrode, presenting perpendicular magnetic anisotropy (PMA). We observe a clear asymmetry of the photocurrent measured under respective right and left polarized light that follows the hysteresis of the magnetic layer. The amplitude of this asymmetry at zero magnetic field decreases with increasing temperatures and can be controlled with the bias. Polarization-resolved photoluminescence is detected in parallel while the device is operated as a photodetector. This demonstrates the multifunctional capabilities of the device and gives valuable insights into the spin relaxation of the electrons in the quantum dots.