Novel electronic properties of a graphene antidot, parabolic dot, and armchair ribbon

S. R.Eric Yang, S. C. Kim

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

Graphene nanostructures have great potential for device applications. However, they can exhibit several counterintuitive electronic properties not present in ordinary semiconductor nanostructures. In this chapter, we review several of these graphene nanostructures. A first example is a graphene antidot that possesses boundstates inside the antidot potential in the presence of a magnetic field. As the range of the repulsive potential decreases in comparison to the magnetic length, the effective coupling constant between the potential and electrons becomes more repulsive, and then, it changes the sign and becomes attractive. This is a consequence of a subtle interplay between Klein tunneling and quantization of Landau levels. In this regime, wavefunctions become anomalous with a narrow probability density peak inside the barrier and another broad peak outside the potential barrier with the width comparable to the magnetic length. The second example is a graphene parabolic dot in the presence of a magnetic field. One counterintuitively finds that resonant quasibound states of both positive and negative energies exist in the energy spectrum. The presence of resonant quasi-bound states of negative energies is a unique property of massless Dirac fermions. Also, when the strength of the potential increases, resonant and nonresonant states transform into discrete anomalous states with a narrow probability density peak inside the well and another broad peak under the potential barrier with the width comparable to the magnetic length. The last example is a one-dimensional electron gas in the lowest energy conduction subband of graphene armchair ribbons. Bulk magnetic properties of it may sensitively depend on the width of the ribbon. For ribbon widths Lx = 3Ma0, depending on the value of the Fermi energy, a ferromagnetic or paramagnetic state can be stable while for Lx = (3M + 1)a0, the paramagnetic state is stable (M is an integer and a0 is the length of the unit cell). Ferromagnetic and paramagnetic states are well suited for spintronic applications.

Original languageEnglish
Title of host publicationGraphene Science Handbook
PublisherCRC Press
Pages183-208
Number of pages26
Volume3-6
ISBN (Electronic)9781466591196
ISBN (Print)9781315374093
Publication statusPublished - 2016 May 1

Bibliographical note

Publisher Copyright:
© 2016 by Taylor & Francis Group, LLC. All rights reserved.

ASJC Scopus subject areas

  • General Physics and Astronomy
  • General Engineering
  • General Materials Science

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