Room-temperature ferromagnetism in graphite driven by two-dimensional networks of point defects

J. Cervenka, M.I. Katsnelson, C.F.J. Flipse

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Abstract

Understanding the mechanism of ferromagnetism in carbon-based materials, which contain only s and p electrons in contrast to traditional ferromagnets based on 3d or 4f electrons, is challenging. Here, we demonstrate direct evidence for ferromagnetic order locally at defect structures in highly oriented pyrolytic graphite (HOPG) with magnetic force microscopy and in bulk magnetization measurements at room temperature. Magnetic impurities have been excluded as the origin of the magnetic signal. The observed ferromagnetism has been attributed to originate from localized electron states at grain boundaries of HOPG, forming two-dimensional arrays of point defects. The theoretical value of the magnetic ordering temperature based on weak interlayer coupling and/or magnetic anisotropy is comparable to the experimental value. The unusual chemical environment of defects bonded in graphitic networks can reveal the role of the s and p electrons, creating new routes for spin transport in carbon-based materials.
Original languageEnglish
Pages (from-to)840-844
JournalNature Physics
Volume5
Issue number11
DOIs
Publication statusPublished - 2009

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point defects
ferromagnetism
graphite
pyrolytic graphite
room temperature
magnetic signals
electrons
magnetic force microscopy
carbon
defects
electron states
interlayers
grain boundaries
routes
impurities
magnetization
anisotropy
temperature

Cite this

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abstract = "Understanding the mechanism of ferromagnetism in carbon-based materials, which contain only s and p electrons in contrast to traditional ferromagnets based on 3d or 4f electrons, is challenging. Here, we demonstrate direct evidence for ferromagnetic order locally at defect structures in highly oriented pyrolytic graphite (HOPG) with magnetic force microscopy and in bulk magnetization measurements at room temperature. Magnetic impurities have been excluded as the origin of the magnetic signal. The observed ferromagnetism has been attributed to originate from localized electron states at grain boundaries of HOPG, forming two-dimensional arrays of point defects. The theoretical value of the magnetic ordering temperature based on weak interlayer coupling and/or magnetic anisotropy is comparable to the experimental value. The unusual chemical environment of defects bonded in graphitic networks can reveal the role of the s and p electrons, creating new routes for spin transport in carbon-based materials.",
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Room-temperature ferromagnetism in graphite driven by two-dimensional networks of point defects. / Cervenka, J.; Katsnelson, M.I.; Flipse, C.F.J.

In: Nature Physics, Vol. 5, No. 11, 2009, p. 840-844.

Research output: Contribution to journalArticleAcademicpeer-review

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AB - Understanding the mechanism of ferromagnetism in carbon-based materials, which contain only s and p electrons in contrast to traditional ferromagnets based on 3d or 4f electrons, is challenging. Here, we demonstrate direct evidence for ferromagnetic order locally at defect structures in highly oriented pyrolytic graphite (HOPG) with magnetic force microscopy and in bulk magnetization measurements at room temperature. Magnetic impurities have been excluded as the origin of the magnetic signal. The observed ferromagnetism has been attributed to originate from localized electron states at grain boundaries of HOPG, forming two-dimensional arrays of point defects. The theoretical value of the magnetic ordering temperature based on weak interlayer coupling and/or magnetic anisotropy is comparable to the experimental value. The unusual chemical environment of defects bonded in graphitic networks can reveal the role of the s and p electrons, creating new routes for spin transport in carbon-based materials.

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