Electronic, magnetic and transport properties of graphene quantum dots with charged impurities için kapak resmi
Electronic, magnetic and transport properties of graphene quantum dots with charged impurities
Polat, Mustafa, author.
Yazar Ek Girişi:
Fiziksel Tanımlama:
xiv, 71 leaves: charts;+ 1 computer laser optical disc.
In this thesis, electronic, magnetic, and transport properties of armchair edged hexagonal and zigzag edged triangular graphene quantum dots (GQDs) are investigated in the presence of charged impurities. In this manner, a special attention has been paid to the Coulomb impurity problem in these structures. The collapse of the wave functions starting from the 1S$_{1/2}$ state is studied in the presence of not only the Coulomb impurity but also in the presence of a Coulomb charged vacancy with the help of tight-binding and extended mean-field Hubbard (MFH) models. Here, we report an interaction induced renormalization of the critical coupling constant ($\beta_{c}$). In addition, our results suggest that the induced charge for the interacting fermions is smaller than that of the non-interacting fermions. Furthermore, the transport coefficients reveal two different characteristics of the subcritical ($\beta$ $<$ $\beta_{c}$) and supercritical ($\beta$ $>$ $\beta_{c}$) regimes. As for the charged vacancy, the bare carbon vacancy induces a local magnetic moment in the hexagonal GQDs, but it is suppressed when the vacancy is charged with the subcritical Coulomb potential. Except the pristine cases of the GQDs, we numerically study a Coulomb impurity problem for the interacting fermions restricted in disordered hexagonal GQDs. In the presence of randomly distributed lattice defects and spatial potential fluctuations induced by Gaussian impurities, the response of $\beta_{c}$ for atomic collapse is mainly investigated by local density of states (LDOS) calculations within the MFH model. We find that both types of disorder cause an amplification of the critical threshold. As for the zigzag edged triangular GQDs, in the presence of the bare vacancy, we exactly obtain the spin splitting with the help of LDOS calculations in the energy spectrums, which are dominated by the edge states around the Fermi level. Similar to the hexagonal GQDs, if the vacancy is charged, the local magnetic moment disappears in these GQDs.
Konu Başlığı:

Yazar Ek Girişi:
Tek Biçim Eser Adı:
Thesis (Doctorale)--İzmir Institute of Technology:Phiysics.

İzmir Institute of Technology:Phiysics--Thesis (Doctoral).
Elektronik Erişim:
Access to Electronic Versiyon.


Materyal Türü
Demirbaş Numarası
Yer Numarası
Durumu/İade Tarihi
Tez T002254 QC611.6.Q35 P76 2020

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