16:00 〜 18:00
▲ [17p-P10-36] First Direct Synthesis of Graphene/Half-metallic Heusler Alloy Heterostructure for Spintronic Device Applications
キーワード：graphene spintronics, half-metalic Heusler alloy, high-vacuum chemical vapor deposition (CVD)
The low spin signal and tiny magneto-resistance is becoming a central issue in graphene-spintronic devices [1] in which conventional ferromagnets (FMs) such as Ni, Co, Fe of low spin polarization were used. Adopting highly spin-polarized material such as half-metal into graphene/FM heterostructure can be the most effective way to enhance the performance of graphene-spintronics device, experimental demonstration, however, is still lacking. This study, for the first time, reports the direct sysnthesis of a new heterostructure consisting of single layer graphene (SLG) by high-vacuum chemical vapor deposition (CVD) on Co2FeGe0.5Ga0.5 (CFGG) Heusler alloy whose half-metallicity has been confirmed experimentally [2].
CFGG layer with a thickness of 50 nm was epitaxially grown on a MgO(001) single-crystal substrate by magnetron sputtering at room temperature. The CFGG/MgO sample was then transferred into a CVD chamber for graphene synthesis. SLG was successfully synthesized on CFGG by optimizing the CVD process. STM image taken from the synthesized SLG/CFGG heterostructure reveals an epitaxial growth of SLG on CFGG.Through a C K-edge XAS spectra study of the SLG/CFGG heterostructure, we found, strikingly, the peak from the π* state of graphene is very sharp, indicating a weak chemical bonding between graphene and CFGG. It makes the SLG/CFGG heterostructure unique from other graphene/FM systems such as SLG/Ni, Co, Fe which have received intensive studies so far. The quasi-freestanding nature of graphene on CFGG makes the SLG/CFGG heterostructure extremely promising for high-performance spintronic devices.
[1] Han et al. Nat. Nanotechnol. 9, 794-807 (2014); [2] Li et al. Appl. Phys. Lett. 103, 042405 (2013).
CFGG layer with a thickness of 50 nm was epitaxially grown on a MgO(001) single-crystal substrate by magnetron sputtering at room temperature. The CFGG/MgO sample was then transferred into a CVD chamber for graphene synthesis. SLG was successfully synthesized on CFGG by optimizing the CVD process. STM image taken from the synthesized SLG/CFGG heterostructure reveals an epitaxial growth of SLG on CFGG.Through a C K-edge XAS spectra study of the SLG/CFGG heterostructure, we found, strikingly, the peak from the π* state of graphene is very sharp, indicating a weak chemical bonding between graphene and CFGG. It makes the SLG/CFGG heterostructure unique from other graphene/FM systems such as SLG/Ni, Co, Fe which have received intensive studies so far. The quasi-freestanding nature of graphene on CFGG makes the SLG/CFGG heterostructure extremely promising for high-performance spintronic devices.
[1] Han et al. Nat. Nanotechnol. 9, 794-807 (2014); [2] Li et al. Appl. Phys. Lett. 103, 042405 (2013).