We demonstrate a large electrical spin injection into GaAs at zero magnetic field thanks to an ultrathin perpendicularly magnetized CoFeB contact of a few atomic planes (1.2 nm). The spin-polarization of electrons injected into GaAs was examined by the circular polarization of electroluminescence from a Spin Light Emitting Diode with embedded InGaAs/GaAs quantum wells. The electroluminescence polarization as a function of the magnetic field closely traces the out-of-plane magnetization of the CoFeB/MgO injector. A circular polarization degree of the emitted light as large as 20% at 25 K is achieved at zero magnetic field. Moreover the electroluminescence circular polarization is still about 8% at room temperature.
@article{arxiv.1404.4527,
title = {Large and robust electrical spin injection into GaAs at zero magnetic field using an ultrathin CoFeB/MgO injector},
author = {S. Liang and T. T. Zhang and P. Barate and J. Frougier and M. Vidal and P. Renucci and B. Xu and H. Jaffrès and J. M. George and X. Devaux and M. Hehn and X. Marie and S. Mangin and H. Yang and A. Hallal and M. Chshiev and T. Amand and H. Liu and D. Liu and X. Han and Z. Wang and Y. Lu},
journal= {arXiv preprint arXiv:1404.4527},
year = {2015}
}