Recombination Time Mismatch and Spin Dependent Photocurrent at a Ferromagnetic-Metal-Semiconductor Tunnel Junction

We report on carrier dynamics in a spin photodiode based on a ferromagnetic-metal-GaAs tunnel junction. We show that the helicity-dependent current is determined not only by the electron spin polarization and spin asymmetry of the tunneling but in great part by a dynamical factor resulting from the competition between tunneling and recombination in the semiconductor, as well as by a specific quantity: the charge polarization of the photocurrent. The two latter factors can be efficiently controlled through an electrical bias. Under longitudinal magnetic field, we observe a strong increase of the signal arising from inverted Hanle effect, which is a fingerprint of its spin origin. Our approach represents a radical shift in the physical description of this family of emerging spin devices.

Automated summary

We report on the carrier dynamics in a spin photodiode based on a ferromagnetic-metal-GaAs tunnel junction. Our findings show that the helicity-dependent current in this device is not only determined by electron spin polarization and spin asymmetry of tunneling, but also by a dynamic factor resulting from the competition between tunneling and recombination in the semiconductor, as well as the charge polarization of the photocurrent. These factors can be efficiently controlled through electrical bias. Additionally, under a longitudinal magnetic field, we observe a significant increase in the signal due to the inverted Hanle effect, which is a characteristic of its spin origin. This approach represents a radical shift in the physical description of this family of emerging spin devices.