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Séminaire « Matériaux 2D/Magnétisme » de l’INSP

Topological insulators and Rashba interfaces for energy harvesting and low power consumption - Juan-Carlos Roja-Sanchez - Mardi 2 juillet à 11 h

INSP - Sorbonne Université - 4 place Jussieu - 75005 Paris - Barre 22-32, 2e étage, salle 201

Juan-Carlos Roja-Sanchez - Institut Jean Lamour à Nancy

Abstract

Materials with large efficiency of spin-charge current interconversion are highly desirable to study new physical phenomena as well as for spintronics applications. Heavy metals or alloys exhibiting large spin-orbit coupling scatter the electrons in opposite directions when they have opposite spin. Thus an injection of charge current yields a transversal spin current in such 3D materials and this is so-called Spin Hall Effect (SHE). We can exploit this effect to manipulate a magnetization in a heavy metal/ferromagnetic structure (HM/FM) [1-3]. On the other hand, new classes of materials such as 3D topological insulator which are insulator in their bulk but hold metallic states in their surfaces are also highly interesting for spintronics. The spin-orbit coupling (SOC) in the 2DEG states at Topological Insulator (TI) or Rashba Interfaces is predicted to be more efficiency that their 3D counterparts for spin-charge current conversion. The underlying physics of charge-spin current interconversion in such 2D systems is different of the SHE and is called Edelstein Effect (EE) [4-7], also known as inverse spin galvanic effect [8]. I will show results of spin-to-charge conversion by spin pumping ferromagnetic resonance experiments and their analysis in term of inverse Edelstein Length [4-7,9]. In particular the large efficiency measured using 2D systems such a Rashba interfaces, Ag/Bi [4] and SrTiO3/LaAlO3 [5], and topological insulators such as -Sn [6]. We have found the highest efficiency at room temperature using the topological insulator α-Sn [6]. Furthermore, some examples of potentials applications for harvesting energy and low power consumption exploiting 2D materials will be discussed.

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[2] J.-C. Rojas-Sánchez et al. Appl. Phys. Lett. 108, 082406 (2016)
[3] T. H. Pham et al. Phys. Rev. Appl. 9, 064032 (2018). ArXiv 1711.10790 (2017)
[4] J.-C. Rojas-Sánchez et al. Nat. Comm 4, 2943 (2013)
[5] E. Lesne, et al. Nat. Mat. 15, 1261 (2016)
[6] J.-C. Rojas-Sánchez et al. Phys. Rev. Lett. 116, 096602 (2016). ArXiv 1509.02973 (2015)
[7] S. Oyarzun, et al. Nat. Comm. 7, 13857 (2016)
[8] S. D. Ganichev et al. Nature 417, 153 (2002)
[9] J.-C. Rojas-Sánchez and A. F. Phys. Rev. Appl. (submitted)