Structure and magnetic properties of curved graphene networks and the effects of bromine and potassium adsorption

Kazuyuki Takai, Tsuyoshi Suzuki, Toshiaki Enoki, Hirotomo Nishihara, Takashi Kyotani

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

The structure and magnetic properties of nanoporous zeolite-templated carbon (ZTC) and its guest-adsorbed systems are investigated using potassium and bromine as guest species. In ZTC, nanopores formed by a three-dimensional curved-graphene network, whose structure is transcribed from the zeolite nanopore structure, are regularly arranged (periodicity: 1.4 nm). The regularity of the nanopore structure is preserved during vacuum heat treatment (<380°C) and potassium adsorption, though it is destroyed by bromine adsorption. The pristine ZTC has localized spins, whose origin is attributed to those created in the region having a negative curvature in the graphene network, as well as to the contribution of an edge state. The spin concentration is estimated as 1 spin/nanopore and is independent of the heat-treatment temperature up to 380°C. In potassium-adsorbed ZTC, potassium atoms forming networked clusters in the nanopores are magnetic and undergo a weak ferromagnetic transition at 24 K. The ZTC spins, which are not directly coupled with the potassium spins through exchange interaction, accurately mirror the magnetic behavior of the potassium spins.

Original languageEnglish
Article number205420
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume81
Issue number20
DOIs
Publication statusPublished - 2010 May 12

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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