MgO thickness dependence of spin injection efficiency in spin-light emitting diodes

Y. Lu , V. G. Truong , Pierre Renucci , M. Tran , H. Jaffres , C. Deranlot (1) , J.-M. George (1) , P. H. Bin , A. Lemaitre (2) , Yunlin Jacques Zheng (3) , Dominique Demaille (3) , Thierry Amand , Xavier Marie (4)

1 Laboratoire Albert Fert (ex-UMPhy Unité mixte de physique CNRS/Thales)
2 LPN - Laboratoire de photonique et de nanostructures
3 INSP - Institut des Nanosciences de Paris
4 INSA Toulouse - Institut National des Sciences Appliquées - Toulouse

We have studied the electron spin injection efficiency from a CoFeB/MgO spin injector into AlGaAs/GaAs semiconductor light emitting diodes. The circular polarization of the electroluminescence signal reaches a value as large as 32% at 100 K under a 0.8 T magnetic field. We show that the spin injection efficiency increases with the increase in the MgO barrier thickness from 1.4 to 4.3 nm. Moreover, a higher spin injection efficiency is obtained for MgO barriers grown at 300 °C compared to the ones grown at room temperature. This effect is attributed to the MgO texturing occurring at high temperatures.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Y. Lu, V. G. Truong, Pierre Renucci, M. Tran, H. Jaffres, et al.. MgO thickness dependence of spin injection efficiency in spin-light emitting diodes. Applied Physics Letters, 2008, 93 (15), pp.2102. ⟨10.1063/1.2999631⟩. ⟨hal-00343586⟩