Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Orbital Magnetism of Graphene Nanostructures: Bulk and Confinement
  Effects   We consider the orbital magnetic properties of non-interacting charge
carriers in graphene-based nanostructures in the low-energy regime. The
magnetic response of such systems results both, frombulk contributions and from
confinement effects that can be particularly strong in ballistic quantum dots.
First we provide a comprehensive study of the magnetic susceptibility $\chi$ of
bulk graphene in a magnetic field for the different regimes arising from the
relative magnitudes of the energy scales involved, i.e. temperature, Landau
level spacing and chemical potential. We show that for finite temperature or
chemical potential, $\chi$ is not divergent although the diamagnetic
contribution $\chi_{0}$ from the filled valance band exhibits the well-known
$-B^{-1/2}$ dependence. We further derive oscillatory modulations of $\chi$,
corresponding to de Haas-van Alphen oscillations of conventional
two-dimensional electron gases. These oscillations can be large in graphene,
thereby compensating the diamagnetic contribution $\chi_{0}$ and yielding a net
paramagnetic susceptibility for certain energy and magnetic field regimes.
Second, we predict and analyze corresponding strong, confinement-induced
susceptibility oscillations in graphene-based quantum dots with amplitudes
distincly exceeding the corresponding bulk susceptibility. Within a
semiclassical approach we derive generic expressions for orbital magnetism of
graphene quantum dots with regular classical dynamics. Graphene-specific
features can be traced back to pseudospin interference along the underlying
periodic orbits. We demonstrate the quality of the semiclassical approximation
by comparison with quantum mechanical results for two exemplary mesoscopic
systems, a graphene disk with infinite mass-type edges and a rectangular
graphene structure with armchair and zigzag edges, using numerical
tight-binding calculations in the latter case.

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The categories of this paper are: gr-qc
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: patt-sol
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The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-ex