Title: Spin-orbit coupling and optical detection of spin polarisation in triangular graphene quantum dots

Authors: P. Potasz; A.D. Güçlü; I. Ozfidan; P. Hawrylak

Addresses: Institute of Physics, Wroclaw University of Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland ' Department of Physics, Izmir Institute of Technology IZTECH, Izmir 35430, Turkey ' Quantum Theory Group, Security and Disruptive Technologies, Emerging Technologies Division, National Research Council of Canada, Ottawa, K1A OR6, Canada ' Physics Department, University of Ottawa, Ottawa, K1N 6N5, Canada; Quantum Theory Group, Security and Disruptive Technologies, Emerging Technologies Division, National Research Council of Canada, Ottawa, K1A OR6, Canada

Abstract: We present a theory of the effect of spin-orbit coupling on optical properties of triangular graphene quantum dots (TGQD). TGQDs with zigzag edges exhibit a degenerate band of states at the Fermi level. For the charge neutral TGQD, the shell is expected to be half-filled by spin polarised electrons leading to finite magnetisation. Using four-band tight-binding and effective Kane-Mele models, we show that, if the TGQD is spin polarised, the low energy optical absorption spectrum reveals two distinct peaks corresponding to left and right circularly polarised light while the unpolarised TGQD shows only one peak. This allows optical detection of spin polarisation, its direction and the strength of spin-orbit coupling in TGQDs.

Keywords: graphene quantum dots; magnetism; optical properties; spintronics; nanotechnology; spin-orbit coupling; optical detection; spin polarisation; four-band tight binding; Kane-Mele models.

DOI: 10.1504/IJNT.2015.067202

International Journal of Nanotechnology, 2015 Vol.12 No.3/4, pp.174 - 181

Received: 08 May 2021
Accepted: 12 May 2021

Published online: 28 Jan 2015 *

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