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Proceedings Paper

Spin relaxation and intervalley scattering in 2D semiconductors (Presentation Recording)
Author(s): Aubrey Hanbicki; Marc Currie; George Kioseoglou; C. Stephen Hellberg; Kathleen M. McCreary; Adam L. Friedman; Berend T. Jonker

Paper Abstract

Monolayer transition metal dichalcogenides, MX2 (M = Mo, W and X = S, Se), are direct-gap semiconductors with some interesting properties. First, the low-dimensional hexagonal structure leads to two inequivalent K-points, K and K’, in the brillioun zone. Second, this valley index and spin are intrinsically coupled, and spin-dependent selection rules enable one to independently populate and interrogate a unique K valley with circularly polarized light. Here we probe the degree of circular polarization of the emitted photoluminescence as function of the photo-excitation energy and temperature to elucidate spin-dependent inter- and intra-valley relaxation mechanisms. Monolayer flakes of MoS2 and MoSe2 show a strong depolarization as the excitation energy is increased. However, WS2 maintains significant polarization for high excitation energies, even at room temperature when properly prepared. We discuss the behavior of the polarization in terms of various phonon assisted intervalley scattering processes. This work was supported by NRL and the NRL Nanoscience Institute

Paper Details

Date Published: 5 October 2015
PDF: 1 pages
Proc. SPIE 9551, Spintronics VIII, 95510Z (5 October 2015); doi: 10.1117/12.2190196
Show Author Affiliations
Aubrey Hanbicki, U.S. Naval Research Lab. (United States)
Marc Currie, U.S. Naval Research Lab. (United States)
George Kioseoglou, Univ. of Crete (Greece)
C. Stephen Hellberg, U.S. Naval Research Lab. (United States)
Kathleen M. McCreary, U.S. Naval Research Lab. (United States)
Adam L. Friedman, U.S. Naval Research Lab. (United States)
Berend T. Jonker, U.S. Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 9551:
Spintronics VIII
Henri-Jean Drouhin; Jean-Eric Wegrowe; Manijeh Razeghi, Editor(s)

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