Consideration on a mechanism of pure circular polarization electroluminescence in a lateral spin-LED

Pure circular polarization (CP) electroluminescence (EL) has been achieved at RT for a lateral-type spin-LED composed of a Fe/crystalline-AlO
_x
spin-injector and a GaAs-based double heterostructure (DH) [ref. 1: PNAS 114, 1783 (2017)]. The annihilation of minority-helicity EL component at relatively high J (> 100 A/cm
²
) is responsible for the observed pure CP, which suggests a mechanism that is entirely different from the occurrence of spin-dependent gain based on the light amplification by stimulated emission of radiation [ref. 2: APL. 93, 042513 (2008)]. In order to account for the observation, we address a mechanism that the spin axis of minority-spin electrons is converted into majority spin axis with a relatively strong CP light field in the event of radiative recombination.