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Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito
Vacuum and Surface Science, 66(9), p.525 - 530, 2023/09
As Au (001) surfaces exhibit a quasi-one-dimensional corrugated structure, Hex-Au(001), its periodicity was predicted to change the electronic structure of graphene when graphene was grown on this surface. Furthermore, the hybridization between graphene and Au is known to introduce bandgap and spin polarization into graphene. Here, we report angle-resolved photoemission spectroscopy and density functional theory calculation of graphene on a Hex-Au(001) surface. A bandgap of 0.2 eV in the graphene Dirac cone was observed at the crossing point of the graphene Dirac cone and Au 6sp bands, indicating that the origin of the bandgap formation was the hybridization between the graphene Dirac cone and Au 6sp band. We discussed the hybridization mechanism and anticipated spin injection into the graphene Dirac cone.
Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito
Physical Review Materials (Internet), 7(1), p.014002_1 - 014002_10, 2023/01
Times Cited Count：4 Percentile：78.07(Materials Science, Multidisciplinary)Au(001) surfaces exhibit a complex reconstructed structure [Hex-Au(001)] comprising a hexagonal surface and square bulk lattices, yielding a quasi-one-dimensional corrugated surface. When graphene was grown on this surface, the periodicity of the corrugated surface was predicted to change the electronic structure of graphene, forming bandgaps and new Dirac points. Furthermore, the graphene-Au interface is promising for bandgap generation and spin injection due to band hybridization. Here, we report the angle-resolved photoemission spectroscopy and density functional calculation of graphene on a Hex-Au(001) surface. The crossing point of the original and replica graphene 
bands showed no bandgap, suggesting that the one-dimensional potential was too small to modify the electronic structure. A bandgap of 0.2 eV was observed at the crossing point of the graphene and Au 
bands, indicating that the bandgap is generated using hybridization of the graphene and Au bands. We discussed the hybridization mechanism and concluded that the R30 configuration between graphene and Au and an isolated electronic structure of Au are essential for effective hybridization between graphene and Au. We anticipate that hybridization between graphene and Au would result in spin injection into graphene.
Terasawa, Tomoo; Yasuda, Satoshi; Matsunaga, Kazuya*; Hayashi, Naoki*; Tanaka, Shinichiro*; Norimatsu, Wataru*; Ito, Takahiro*; Machida, Shinichi*; Asaoka, Hidehito
no journal, ,
Graphene grown on Hex-Au(001) substrate shows an energy gap in its -band. Previous reports speculated that the periodic potential of Hex-Au(001) resulted in the energy gap formation in the -band of graphene. In the present study, we found by angle-resolved photoemission spectroscopy that the hybridyzation of sp-band of Hex-Au(001) and -band of graphene created the energy gap in the -band of graphene.
Terasawa, Tomoo; Matsunaga, Kazuya*; Hayashi, Naoki*; Ito, Takahiro*; Tanaka, Shinichiro*; Yasuda, Satoshi; Asaoka, Hidehito
no journal, ,
As a Hex-Au(001) surface shows one-dimensional corrugation and is chemically inert, it has been employed to study the effect of one-dimensional potential on graphene. Such potential has been expected to make the band structure of graphene anisotropic, which shows the mini-gap at the zone boundary across the potential and the high group velocity along the potential. However, the bandgap in the graphene on Hex-Au(001) was only indirectly suggested by scanning tunneling spectroscopy. Here, we report the band structure of graphene on Hex-Au(001) substrates using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculation. The ARPES image shows the bandgap in the graphene band close to the Au 6sp band. The DFT calculated band structure shows the bandgap not at the crossing point of the graphene bands but that of graphene and Au 6sp bands. We thus conclude that the bandgap originates from the hybridization between graphene and Au. This hybridization is similar to that observed in the graphene and Au interface on the SiC substrate. We expect that the hybridization between graphene and Au is essential as the Rashba splitting of 100 meV was observed around the gap.
Matsunaga, Keita*; Aizawa, Koki*; Ogawa, Hiroki; Utsugi, Mitsuru*; Yoshimura, Ryokei*; Yamazaki, Kenichi*; Uchida, Kazunari*
no journal, ,
no abstracts in English
