Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

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

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Publisher: search.filters.publisher.American Physical SocietySubject: search.filters.subject.Magnetic moments

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Collapse of the Vacuum in Hexagonal Graphene Quantum Dots: a Comparative Study Between Tight-Binding and Mean-Field Hubbard Models
    (American Physical Society, 2020) Polat, Mustafa; Sevinçli, Haldun; Sevinçli, Haldun; Güçlü, Alev Devrim; Güçlü, Alev Devrim; Polat, Mustafa; 04.05. Department of Pyhsics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    In this paper, we perform a systematic study on the electronic, magnetic, and transport properties of the hexagonal graphene quantum dots (GQDs) with armchair edges in the presence of a charged impurity using two different configurations: (1) a central Coulomb potential and (2) a positively charged carbon vacancy. The tight-binding and the half-filled extended Hubbard models are numerically solved and compared with each other in order to reveal the effect of electron interactions and system sizes. Numerical results point out that off-site Coulomb repulsion leads to an increase in the critical coupling constant to beta(c) = 0.6 for a central Coulomb potential. This critical value of beta is found to be independent of the GQD size, reflecting its universality even in the presence of electron-electron interactions. In addition, a sudden downshift in the transmission peaks shows a clear signature of the transition from subcritical beta < beta(c) to the supercritical beta > beta(c) regime. On the other hand, for a positively charged vacancy, collapse of the lowest bound state occurs at beta(c) = 0.7 for the interacting case. Interestingly, the local magnetic moment, induced by a bare carbon vacancy, is totally quenched when the vacancy is subcritically charged, whereas the valley splittings in electron and hole channels continue to exist in both regimes.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Muon Anomalous Magnetic Moment Constraints on Supersymmetric U(1)?? Models
    (American Physical Society, 2010) Cincioğlu, Elif; Kırca, Zerrin; Sert, Hale; Solmaz, Saime; Solmaz, Levent; Hiçyılmaz, Yaşar; 01. Izmir Institute of Technology
    We study the anomalous magnetic moment of the muon in supersymmetric E 6 models and generic U(1)′ models to probe the model reactions and to find constraints on the large parameter space of these models. For future searches, by imposing the existing bounds coming from collider searches and theoretical considerations upon the U(1)′ model parameters, we examine the lightest Higgs boson mass mh and the mass of the additional Z boson mZ2 in such singlet extensions of the MSSM. We observed that not only supersymmetric E6 models but also generic U(1)′ models are sensitive to the imposition of the considered bounds. Indeed, without the muon anomaly constraints E6 models and generic U(1)′ models can predict mh as large as ∼150GeV and ∼180GeV, respectively. However, in addition to the mentioned constraints when a 1σ range for the anomalous magnetic moment of the muon is considered, we observe that generic U(1)′ models do not favor the mass of the lightest Higgs boson to be larger than 140 GeV; it should be smaller than 135 GeV in E6 models. © 2010 The American Physical Society