Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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  • Article
    Citation - WoS: 10
    Citation - Scopus: 10
    Spin-Spin Correlations of Magnetic Adatoms on Graphene
    (American Physical Society, 2015) Güçlü, Alev Devrim; Bulut, Nejat
    We study the interaction between two magnetic adatom impurities in graphene using the Anderson model. The two-impurity Anderson Hamiltonian is solved numerically by using the quantum Monte Carlo technique. We find that the interimpurity spin susceptibility is strongly enhanced at low temperatures, significantly diverging from the well-known Ruderman-Kittel-Kasuya-Yoshida result which decays as R-3.
  • Article
    Citation - WoS: 26
    Citation - Scopus: 27
    Electron-Electron Interactions and Topology in the Electronic Properties of Gated Graphene Nanoribbon Rings in Möbius and Cylindrical Configurations
    (American Physical Society, 2013) Güçlü, Alev Devrim; Grabowski, Marek; Hawrylak, Pawel
    We present a theory of the electronic properties of gated graphene nanoribbon rings with zigzag edges in Möbius and cylindrical configurations. The finite width opens a gap and nontrivial topology of the Möbius ring leads to a single edge with edge states with an induced, effective gauge field, in analogy to topological insulators. The single zigzag edge leads to a shell of degenerate states at the Fermi level and a ferromagnetic (FM) ground state at half-filling, i.e., at charge neutrality, due to electron-electron interactions. For fractional fillings, both the magnetic moment and the energy gap are found to oscillate as a function of the shell filling. In cylindrical rings, the two edges lead to AF ground state at half-filling but FM ground state at fractional fillings.
  • 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.