Controlling surface charge and spin density oscillations by Dirac plasmon interaction in thin topological insulators

M. Ameen Poyli, M. Hrtoň, I. A. Nechaev, A. Y. Nikitin, P. M. Echenique, V. M. Silkin, J. Aizpurua, and R. Esteban
Phys. Rev. B 97, 115420 – Published 15 March 2018

Abstract

Thin topological insulator (TI) films support optical and acoustic plasmonic modes characterized by effective net charge or net spin density, respectively. We combine many-body and electromagnetic calculations to study how these modes can be selectively excited at films and nanodisks at infrared and THz frequencies. We first discuss the excitation of propagating plasmons in a thin film by a point dipolar source. We emphasize how changing the distance between the dipolar source and the film allows us to control the relative strength of the acoustic and optical plasmons and thus to excite net-spin or net-charge waves on demand. The acoustic and optical modes in a nanodisk structure can be efficiently tuned by changing the size of the disk or by applying electrostatic gating. Furthermore, these modes can be confined to regions of dimensions much smaller than the wavelength. The control of the excitation of acoustic and optical modes indicates that thin topological insulators are a promising system to manipulate the spin and charge properties of the plasmonic response, with potential applications in fast, compact, and electrically-controlled spintronic devices.

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  • Received 10 July 2017

DOI:https://doi.org/10.1103/PhysRevB.97.115420

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. Ameen Poyli1,2,3, M. Hrtoň4, I. A. Nechaev1,5,6, A. Y. Nikitin2,7,8, P. M. Echenique1,2,9, V. M. Silkin2,8,9, J. Aizpurua1,2, and R. Esteban2,8,*

  • 1Centro de Física de Materiales CFM - MPC, Centro Mixto CSIC-UPV/EHU, 20018 San Sebastián-Donostia, Basque Country, Spain
  • 2Donostia International Physics Center (DIPC), 20018 San Sebastián-Donostia, Basque Country, Spain
  • 3Department of Physics and Nanotechnology, SRM University, Kattankulathur, 603203, Tamil Nadu, India
  • 4Central European Institute of Technology, Brno University of Technology, Technická 10, 616 00 Brno, Czech Republic
  • 5Tomsk State University, Laboratory of Nanostructured Surfaces and Coatings, 634050, Tomsk, Russia
  • 6Saint Petersburg State University, Laboratory of Electronic and Spin Structure of Nanosystems, 198504, Saint Petersburg, Russia
  • 7CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
  • 8IKERBASQUE, Basque Foundation for Science, 48013, Bilbao, Spain
  • 9Departamento de Física de Materiales UPV/EHU, Facultad de Ciencias Químicas, UPV/EHU, Apdo. 1072, 20080 San Sebastián-Donostia, Basque Country, Spain

  • *ruben_esteban@ehu.eus

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Issue

Vol. 97, Iss. 11 — 15 March 2018

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