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Unique atomic structures at the edges of graphenes yield a variety of interesting phenomena. In spite of carbon-based material with only sp bonds, the zigzag-type atomic structure of graphene edges theoretically produces spontaneous spin polarization of electrons due to mutual Coulomb interaction of extremely high electron density of states localizing at the flat energy band. However, spin-based phenomena have been experimentally observed only in defect-related carbon systems. Here, we fabricate honeycomb-like arrays of low-defect hexagonal nanopores (graphene nanomeshes; GNMs) on graphenes, which produce a large amount of pore edges, by using a nonlithographic method (nanoporous alumina templates). We find large-magnitude ferromagnetism arising from polarized electron spins localizing at the zigzag-nanopore edges of monolayer GNMs. Moreover, spin pumping effect depending on GNM structures is found for magnetic fields applied in parallel with the few-layer GNM planes. These promise to be a realization of rare-element free magnets and also novel all-carbon spintronic devices. [ABSTRACT FROM AUTHOR]

We report on first-principles calculations of spin-dependent properties in graphene induced by its interaction with a nearby magnetic insulator (europium oxide, EuO). The magnetic proximity effect results in spin polarization of graphene π orbitals by up to 24%, together with a large exchange-splitting band gap of about 36 meV. The position of the Dirac cone is further shown to depend strongly on the graphene-EuO interlayer. These findings point toward the possible engineering of spin gating by the proximity effect at a relatively high temperature, which stands as a hallmark for future all-spin information processing technologies. [ABSTRACT FROM AUTHOR]

The zigzag-type atomic structure at edges of graphenes theoretically produces flat energy band. Because electrons have infinite effective mass at the flat band, they localize at zigzag edges with high densities. The localized electron spins are spontaneously polarized due to mutual Coulomb interaction in spite of a material consisting of only carbon atom with sp2 bonds. However, in most experimental studies, spin polarization (such as ferromagnetism) has been observed in defect-related carbon systems. Here, we fabricate honeycomb-like arrays of low-defect hexagonal antidots (nanopores) terminated by hydrogen atoms on graphenes. They are prepared by a non-lithographic method using nanoporous alumina templates. We find large-magnitude ferromagnetism arising from polarized electron spins localizing at the zigzag antidot edges. Moreover, weak hysteresis loop in magnetoresistance and also spin pumping effect are found for perpendicular and parallel magnetic fields applied to the few-layer antidot lattices with larger inter-antidot space. These promise to be a realization of rare-element free magnets and also novel spintronic devices such as all-carbon spin transistors. [ABSTRACT FROM AUTHOR]

Theoretically, the so-called zigzag edge of graphenes provides localized electrons due to the presence of flat energy bands near the Fermi level. Spin interaction makes the localized spins strongly polarized, yielding ferromagnetism. However, in most experimental studies, ferromagnetism has been observed in uncontrollable and complicated carbon-based systems. Here, we fabricate graphenes with honeycomblike arrays of hexagonal nanopores, which have a large ensemble of hydrogen-terminated and low-defect pore edges that are prepared by a nonlithographic method (nanoporous alumina templates). We observe large-magnitude ferromagnetism derived from electron spins localizing at the zigzag nanopore edges. This promises to be a realization of graphene magnets and novel spintronic devices. [ABSTRACT FROM AUTHOR]

The so-called zigzag edge of graphenes theoretically has localized electrons due to the presence of flat energy bands near the Fermi level. The localized electron spins are strongly polarized, resulting in ferromagnetism. We fabricate graphenes with honeycomb-like arrays of hydrogen-terminated and low-defect hexagonal nanopores by a nonlithographic method using nanoporous alumina templates. We report large-magnitude room-temperature ferromagnetism caused by electron spins localizing at the zigzag nanopore edges. This promises to be a realization of rare-element free, controllable, transparent, flexible, and mono-atomic layer magnets and novel spintronic devices. [ABSTRACT FROM AUTHOR]