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Home page > LPCNO > Seminars > 2015 > Towards Spin-LED and Spin-VECSEL operation at magnetic remanence"

Towards Spin-LED and Spin-VECSEL operation at magnetic remanence"

Date : 15/01/2015 à 14:00

Titre : Towards Spin-LED and Spin-VECSEL operation at magnetic remanence.

Intervenant : Julien Frougier

Provenance : Unité Mixte de Physique CNRS/Thales, 91767 Palaiseau, France

Salle : Salle de Séminaire - LPCNO

Résumé: This project, developed in collaboration between the Unité Mixte de physique CNRS/Thales and Thales Research & Technology, proposes to explore a new paradigm of spin-information propagation over very long distances by encoding it on laser light polarization[1,2]. Such highly multidisciplinary research, at the interface of spintronics, optoelectronics and photonics could provide applications such as spin-information amplifiers, lasers with improved performances, spin driven reconfigurable optical interconnects and fast modulation dynamics.

Semiconductor lasers with vertical geometries such as Vertical External-Cavity Surface-Emitting Lasers (VECSELs) based on 1⁄2-VCSELs stand out as perfect candidates to meet the key requirements for these applications. Impressive results have already been demonstrated using optically spin-injected monolithic VCSELs in a pulsed regime[3]. However, efficient conversion of an electrically injected spin-current into circularly-polarized light remains a challenge[4].

This presentation addresses theoretically and experimentally optical and electrical spin-injection in (100)-oriented InGaAs/GaAsP multiple-quantum-well VECSEL structures. Using an optical spin-injection we were able to demonstrate switching between two circularly-polarized states at room temperature[5]. We also examined the conditions for the control of the electromagnetic field polarization by discussing the competition between the linear birefringence, intrinsic to the 1⁄2-VCSELs, and the circular gain dichroism originating from the spin-injection. Within the context of electrical spin-injection, an ultra-thin MgO/CoFeB/Ta spin-injector with Perpendicular Magnetic Anisotropy (PMA) at remanence has been experimentally developed and optimized using III-V semiconductor LEDs[6,7]. This achievement was made possible thanks to a strong collaboration between the Unité Mixte de physique CNRS/Thales, the LPCNO and the Institute Jean-Lamour. Furthermore, laser operation was established despite the insertion of such highly absorbent ferromagnetic spin-injectors inside the laser cavity. Finally, we showed encouraging preliminary results on electrical spin-injection in VECSELs and we will discuss the future challenges that need to be met in order to implement a fully operational electrically spin-injected VECSEL.

[1] I. Zutic, R. Oszwaldowski, J. Lee and C. Gothgen, Handbook of spin transport and magnetism, Chap. 38 ”Semiconductor Spin-Lasers”, p. 731–745 (Edited by E. Y. Tsymbal and I. Zutic, CRC Press, 2011)

[2] I. Zutic et al., Nat. Nanotech. 9, 750 (2014)

[3] S. Iba et al., APL 98, 081113 (2011)

[4] P. Bhattacharya et al., APL 89, 182504 (2006)

[5] J. Frougier et al., Applied Physics Letters 103, 252402 (2013)

[6] P. Barate, et al., Applied Physics Letters 105, 012404 (2014)

[7] S. Liang, et al., Physical Review B 90, 085310 (2014)