Spin States in Graphene Quantum Dots

Güttinger, J.; Frey, Tobias; Stampfer, Christoph; Ihn, Thomas; Ensslin, Klaus

doi:10.1103/physrevlett.105.116801

Cited by 133 publications

(156 citation statements)

References 29 publications

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“…Although one possibility is that the g-factor is much smaller in the graphene plane, studies of graphite have shown this parameter to be isotropic [58]. A more likely explanation is an extrinsic, substrate-induced, anisotropy, and we note that a recent study of the spin states of graphene quantum dots also found a much weaker spin splitting for B || [59]. In fact, for B ⊥ these authors observed the onset of Zeeman splitting beyond 2 -4 T, consistent with our data in Fig.…”

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confidence: 64%

Nonergodicity and microscopic symmetry breaking of the conductance fluctuations in disordered mesoscopic graphene

et al. 2012

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We show a dramatic deviation from ergodicity for the conductance fluctuations in graphene. In marked contrast to the ergodicity of dirty metals, fluctuations generated by varying magnetic field are shown to be much smaller than those obtained when sweeping Fermi energy. They also exhibit a strongly anisotropic response to the symmetry-breaking effects of a magnetic field, when applied perpendicular or parallel to the graphene plane. These results reveal a complex picture of quantum interference in graphene, whose description appears more challenging than for conventional mesoscopic systems.

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confidence: 64%

Nonergodicity and microscopic symmetry breaking of the conductance fluctuations in disordered mesoscopic graphene

et al. 2012

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“…6 Recently, spin splitting in graphene and bilayer graphene in high magnetic field was experimentally analyzed by Kurganova et al, 10 who found that the g factor in graphene is enhanced and attributed this to electron-electron interaction effects. The spin splitting of the states in graphene 11 and graphene quantum dots 12 was also studied in a parallel magnetic field.…”

Section: Introductionmentioning

confidence: 99%

Spin polarization andg-factor enhancement in graphene nanoribbons in a magnetic field

Ihnatsenka

Zozoulenko

2012

Phys. Rev. B

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We provide a systematic quantitative description of spin polarization in armchair and zigzag graphene nanoribbons (GNRs) in a perpendicular magnetic field. We first address spinless electrons within the Hartree approximation, studying the evolution of the magnetoband structure and formation of the compressible strips. We discuss the potential profile and the density distribution near the edges and the difference and similarities between armchair and zigzag edges. Accounting for the Zeeman interaction and describing the spin effects via the Hubbard term, we study the spin-resolved subband structure and relate the spin polarization of the system at hand to the formation of the compressible strips for the case of spinless electrons. At high magnetic field the calculated effective g factor varies around a value of g * ≈ 2.25 for armchair GNRs and g * ≈ 3 for zigzag GNRs. An important finding is that in zigzag GNRs the zero-energy mode remains pinned to the Fermi energy and becomes fully spin polarized for all magnetic fields, which, in turn, leads to a strong spin polarization of the electron density near the zigzag edge. Because of this the effective g factor in zigzag GNRs is strongly enhanced at low fields reaching values up to g * ≈ 30. This is in contrast to armchair GNRs, where the effective g factor at low field is close to its bare value, g = 2.

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“…Finally, it is noteworthy that spin splitting in graphene 36 and graphene quantum dots 37 was also experimentally studied in a parallel magnetic filed. It was concluded that in this case the effective g factor does differ from its free-electron value.…”

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confidence: 99%

Interaction-induced enhancement ofgfactor in graphene

2012

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We study the effect of electron interaction on the spin splitting and the g factor in graphene in a perpendicular magnetic field using the Hartree and the Hubbard approximations within the Thomas-Fermi model. We found that the effective g factor is enhanced in comparison to its free-electron value g = 2 and oscillates as a function of the filling factor ν in the range 2 g * 4 reaching maxima at ν = 4N = 0, ± 4, ± 8, . . . and minima at ν = 4 N + 1 2 = ±2, ± 6, ± 10, . . ., with N being the Landau level index. We outline the role of charged impurities in the substrate, which are shown to suppress the oscillations of the g * factor. This effect becomes especially pronounced with the increase of the impurity concentration, when the effective g factor becomes independent of the filling factor, reaching a value of g * ≈ 2.3. A relation to the recent experiment is discussed.

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Spin States in Graphene Quantum Dots

Cited by 133 publications

References 29 publications

Nonergodicity and microscopic symmetry breaking of the conductance fluctuations in disordered mesoscopic graphene

Nonergodicity and microscopic symmetry breaking of the conductance fluctuations in disordered mesoscopic graphene

Spin polarization andg-factor enhancement in graphene nanoribbons in a magnetic field

Interaction-induced enhancement ofgfactor in graphene

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