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RKKY interaction in heavily vacant graphene

Habibi, A ; Sharif University of Technology | 2013

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  1. Type of Document: Article
  2. DOI: 10.1088/0953-8984/25/37/375501
  3. Publisher: 2013
  4. Abstract:
  5. Dirac electrons in clean graphene can mediate the interactions between two localized magnetic moments. The functional form of the RKKY interaction in pristine graphene is specified by two main features: (i) an atomic-scale oscillatory part determined by a wavevector → connecting the two valleys; with doping another longer range oscillation appears which arises from the existence of an extended Fermi surface characterized by a momentum scale kF; (ii) an algebraic Rα decay in large distances where the exponent α=-3 is a distinct feature of undoped Dirac sea in two dimensions. In this work, we investigate the effect of a few per cent vacancies on the above properties. Depending on the doping level, if the chemical potential lies on the linear part of the density of states, the exponent αremains at -3 even in vacant graphene. Otherwise αreduces towards more negative values. Presence of vacancies washes out both atomic-scale and Friedel oscillations of the RKKY interaction. The absence of atomic-scale oscillations indicates the destruction of two-valley structure of the parent graphene material. However, the absence of Friedel oscillations upon alloying with vacancies indicates that a quantum ground state of heavily vacant doped graphene is not given by a unique kF momentum scale
  6. Keywords:
  7. Density of state ; Dirac electrons ; Friedel oscillations ; Functional forms ; Localized magnetic moments ; Negative values ; Quantum ground state ; RKKY interactions ; Atoms ; Magnetic moments ; Graphene ; Chemical model ; Computer simulation ; Electron ; Magnetic field ; Surface property ; Chemistry ; Magnetic Fields ; Electrons ; Graphite ; Models, Chemical ; Surface Properties
  8. Source: Journal of Physics Condensed Matter ; Volume 25, Issue 37 , August , 2013 ; 09538984 (ISSN)
  9. URL: http://iopscience.iop.org/article/10.1088/0953-8984/25/37/375501/meta;jsessionid=E36EB83B593EB64EA20E078302B83461.c1