Spin-dependent recombination in GaAsN alloys

TL;DR

This study demonstrates room-temperature spin-dependent recombination in GaAsN alloys, revealing significant effects on photoluminescence and electron spin polarization, and estimates the electron spin relaxation time to be around 1 nanosecond.

Contribution

It provides the first detailed experimental analysis of SDR effects in GaAsN alloys at room temperature, including spin polarization and relaxation dynamics.

Findings

Photoluminescence intensity decreases by over 3 times with polarization or magnetic field changes.

Conduction electron spin polarization reaches 35% with increased pump intensity.

Electron spin relaxation time is estimated at approximately 1 nanosecond.

Abstract

The spin-dependent recombination (SDR) has been observed in GaAs_{1-x}N_{x} (x = 2.1, 2.7, 3.4%) at room temperature. It reveals itself in a decrease of the edge photoluminescence (PL) intensity by more than a factor of 3 when either the polarization of the exciting light is changed from circular to linear or the transverse magnetic field of ~300 gauss (G) is applied. The interband absorption of the circularly polarized light results in a spin polarization of conduction electrons, which reaches 35% with increasing the pump intensity. The effects observed are explained by dynamical polarization of deep paramagnetic centers and spin-dependent capture of conduction electrons by these centers. The PL depolarization in a transverse magnetic field (Hanle effect) allows us to estimate the electron spin relaxation time in the range of 1 ns. Theoretically, it has been concluded that, due to the SDR, this long time is controlled by slow spin relaxation of bound electrons. In all the three alloy samples, a positive sign of the bound-electron g-factor is determined experimentally from the direction of their mean spin rotation in the magnetic field.