Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

Browse

Filters

2013 - 20152

Settings

Author: search.filters.author.Hawrylak, P.

Search Results

Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Spin-Orbit Coupling and Optical Detection of Spin Polarisation in Triangular Graphene Quantum Dots
    (Inderscience Enterprises Ltd., 2015) Potasz, P.; Güçlü, Alev Devrim; Özfidan, I.; Hawrylak, P.
    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.
  • Article
    Citation - WoS: 38
    Citation - Scopus: 41
    Zero-Energy States of Graphene Triangular Quantum Dots in a Magnetic Field
    (American Physical Society, 2013) Güçlü, Alev Devrim; Potasz, P.; Hawrylak, P.
    We present a tight-binding theory of triangular graphene quantum dots (TGQD) with zigzag edge and broken sublattice symmetry in an external magnetic field. The lateral size quantization opens an energy gap, and broken sublattice symmetry results in a shell of degenerate states at the Fermi level. We derive a semianalytical form for zero-energy states in a magnetic field and show that the shell remains degenerate in a magnetic field, in analogy to the zeroth Landau level of bulk graphene. The magnetic field closes the energy gap and leads to the crossing of valence and conduction states with the zero-energy states, modulating the degeneracy of the shell. The closing of the gap with increasing magnetic field is present in all graphene quantum dot structures investigated irrespective of shape and edge termination.