Very efficient electrical spin injection (/detection) into quantum dots at zero magnetic field

Abstract : In this paper, we demonstrate a very efficient electrical spin injection into an ensemble of InAs/InGaAs quantum dots at zero magnetic field. The circular polarization of the electroluminescence coming from the dots, which are embedded into a GaAs-based Spin Light Emitting diode reaches a value as large as 20% at low temperature. In this device, no external magnetic field is required in order to inject or read spin polarization thanks to the use of an ultrathin CoFeB electrode (1.1 nm), as well as p-doped quantum dots (with one hole per dot in average) as an optical probe. The electroluminescence circular polarization of the dots follows the hysteresis loop of the magnetic layer and decreases as a function of bias for large voltages. In a reverse way, we have also investigated the possibility to use such a device as a photodetector presenting a photon helicity-dependent photocurrent. We observe a weak asymmetry of photocurrent under right and left polarized light that follows the hysteresis cycle of the magnetic layer, and the effect decreases for increasing temperatures and can be controlled by the bias
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Conference papers
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https://hal.insa-toulouse.fr/hal-02053950
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Submitted on : Friday, March 1, 2019 - 3:58:00 PM
Last modification on : Thursday, October 31, 2019 - 2:02:24 PM

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  • HAL Id : hal-02053950, version 1

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Fabian Cadiz, Delphine Lagarde, Shiheng Liang, Bingshan Tao, Julien Frougier, et al.. Very efficient electrical spin injection (/detection) into quantum dots at zero magnetic field. Spintronics X, Aug 2017, San Diego, France. pp.48. ⟨hal-02053950⟩

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