A master thesis from Aalborg University
Magnetic Nanostructured Graphene
Author(s)
Term
4. term
Education
Publication year
2013
Submitted on
2013-09-02
Pages
81 pages
Abstract
Electronic properties of nanostructured graphene are determined in the framework of a third nearest neighbour mean field Hubbard model. Band gaps and magnetic ground states of 0D graphene flakes, 1D graphene nanoribbons and 2D triangular graphene antidots with hexagonal holes are considered. Structures with sublattice imbalance are found to be ferromagnetic, while for balanced sublattices we identify a critical size above which the ground state is antiferromagnetic. The antiferromagnetic ground state increases the band gap, giving large band gaps with a profound effect on the optical response. Finally, we examine the stability of the antiferromagnetic states for increased temperature and doping. We find the structures to depolarize for T ∼ 1000 K and doping ∼ 1% impurities.
Keywords
graphene ; nanostructured ; ribbon ; Hubbard ; mean-field ; tight binding ; antidot ; GAL ; GHAL ; flakes ; spin ; spin polarized ; magnetic ; ZGNR ; AGNR ; doping ; optical response ; optical conductivity ; ferromagnetic ; antiferromagnetic ; exact diagonalization ; nanoribbon ; hexagonal holes ; Lieb's theorem ; band gap ; sublattice imbalance ; critical size ; second quantization ; density of states ; projected density of states ; DOS ; PDOS ; simple scaling law ; zigzag ; armchair
Documents
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