SHIKOH Eiji

写真a

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Title

Professor

Laboratory location

Sugimoto Campus

Degree 【 display / non-display

  • Tohoku University -  Ph.D in Engineering

  • Tohoku University -  Master of Engineering

  • Tohoku University -  Bachelor of Engineering

Research Areas 【 display / non-display

Magnetics, Spintronics

Research Interests 【 display / non-display

Spintronics, Spin pumping, Magnetism control by light irradiation, Molecular spintronics, ferromagnetic resonance, magnetic thin films, Magnetics, Surface and interface magnetism, LED

Research Career 【 display / non-display

  • Research for development of new devices with spintronics

      Project Year :

    1999.04
    -
    Today

    Keyword in research subject:  Smart Energy, Spintronics, Magnetics

  • Spin transport induced by the spin-pumping at room temperature

      Project Year :

    2010.04
    -
    Today

Awards & Honors 【 display / non-display

  • Takei-Award (Encouragement award for young scientsits) of Magnetics Societ of Japan.

    2000  

Current Career 【 display / non-display

  • Osaka City University   Graduate School of Engineering   Physical Electronics and Informatics Course   Professor  

Career 【 display / non-display

  • 2013.04
    -
    2018.09

    Osaka City University   Graduate School of Engineering   Assistant Professor

  • 2011
    -
    2013

    Osaka University   Graduate School of Engineering Science   Associate Professor

  • 2010
    -
    2011

    Osaka University   Graduate School of Engineering Science   Assistant professor

  • 2007
    -
    2010

    Japan Advanced Institute of Science and Technology   School of Materials Science   Assistant Professor

  • 2006
    -
    2007

    Japan Advanced Institute of Science and Technology   School of Materials Science   Assistant Professor

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Graduate School 【 display / non-display

  •  
    -
    2004

    Tohoku University  Graduate School, Division of Engineering  Department of Applied Physics 

  •  
    -
    2001

    Tohoku University  Graduate School, Division of Engineering  Department of Applied Physics 

Graduating School 【 display / non-display

  •  
    -
    1997

    Tohoku University   Faculty of Engineering   Department of Applied Physics

 

Published Papers 【 display / non-display

  • Low-magnetic field effect and electrically detected magnetic resonance measurements of photocurrent in vacuum vapor deposition films of weak charge-transfer pyrene/dimethylpyromellitdiimide (Py/DMPI) complex

    Hagi Shogo, Kato Ken, Hinoshita Masumi, Yoshino Harukazu, Shikoh Eiji, Teki Yoshio

    JOURNAL OF CHEMICAL PHYSICS  151 ( 24 )  2019.12  [Refereed]

    DOI

  • Pure spin current in a robust pigment-red film

    Kazuhiro Nishida, Yoshio Teki, Eiji Shikoh

    cond-mat:arXiv  1908   07730-1 - 07730-15 2019.08

     View Summary

    We report the spin current properties in a pigment-red (perylene-3,4,9,10-tetracarboxylic dianhydride: PTCDA) film prepared by thermal evaporation. In a palladium(Pd)/PTCDA/Ni80Fe20 tri-layer sample, a pure spin-current is generated in the PTCDA layer by the spin-pumping of the Ni80Fe20. The spin current is absorbed into the Pd layer, converted into a charge current with the inverse spin-Hall effect in Pd, and detected as an electromotive force. This is clear evidence for the pure spin current in a PTCDA film, and it is confirmed that a PTCDA film is useful not only as a robust protection layer material but also as a spintronic material.

  • Spin Transport in Poly-Acene Films and the Derivative Films by Using the Spin Pumping

    Yuji Tanaka, Taisei Kono, Yoshio Teki, Eiji Shikoh

    IEEE TRANSACTIONS ON MAGNETICS  55   1400304-1 - 1400304-4 2019.02  [Refereed]

     View Summary

    The spin transport in thermally-evaporated tetracene films and 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) films by using the spin-pumping-induced spin injection method was challenged at room temperature. The spin transport in the TIPS-pentacene films was demonstrated, while the spin transport in tetracene films was not succeeded. For tetracene films, reconstruction of the prepared films was occurred due to the high vapor pressure and it might be caused the deformation of ferromagnetic material as the spin injector.

    DOI

  • Self-induced inverse spin-Hall effect in an iron and a cobalt single-layer films themselves under the ferromagnetic resonance

    Kazunari Kanagawa, Yoshio Teki, Eiji Shikoh

    AIP ADVANCES  8 ( 5 ) 055910-1 - 055910-6 2018.05  [Refereed]

     View Summary

    The inverse spin-Hall effect (ISHE) is produced even in a “single-layer” ferromagnetic material film. Previously, the self-induced ISHE in a Ni80Fe20 film under the ferromagnetic resonance (FMR) was discovered. In this study, we observed an electromotive force (EMF) in an iron (Fe) and a cobalt (Co) single-layer films themselves under the FMR. As origins of the EMFs in the films themselves, the ISHE was main for Fe and dominant for Co, respectively 2 and 18 times larger than the anomalous Hall effect. Thus, we demonstrated the self-induced ISHE in an Fe and a Co single-layer films themselves under the FMR.

    DOI

  • Photoconductivity and magnetoconductance effects on vacuum vapor deposition films of weak charge-transfer complexes

    Ken Kato, Shogo Hagi, Masumi Hinoshita, Eiji Shikoh, Yoshio Teki

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS  19 ( 29 ) 18845 - 18853 2017.08  [Refereed]

     View Summary

    Thin films of weak charge-transfer (CT) complexes (pyrene/dimethylpyromellitdiimide or pyrene/pyromellitic dianhydride) were prepared on an interdigitated platinum electrode by vacuum vapor deposition. Their photoconductivity and magnetoconductance (MC) effects were investigated, and mobile triplet excitons (probably CT excitons) were detected by time-resolved ESR (TRESR) at room temperature. The MC effect on the photocurrent was observed and analyzed by quantum-mechanical simulation assuming two types of collision mechanisms between the electron and hole carriers and between the trapped triplet excitons and mobile carriers. A successful simulation was achieved when the parameters (g, D, E, and polarization) determined by TRESR and the effective hyperfine splitting estimated from an ab initio molecular-orbital calculation were used.

    DOI

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Review Papers (Misc) 【 display / non-display

  • Realization of highly efficient spin injection using Fe_3Si by dynamical method

    ICHIBA Kouki, ANDO Yuichiro, YAMADA Shinya, SHIKOH Eiji, SHINJO Teruya, HAMAYA Kohei, SHIRAISHI Masashi

    The Institute of Electronics, Information and Communication Engineers, IEICE technical report. Magnetic recording  113 ( 407 ) 21 - 24 2014  [Refereed]  [Invited]

     View Summary

    Recently, control of pure spin current have attracted a great deal of attention as a method of dissipation-free information propagation. An electrical method, general spin-generation method, made significant advances and is utilized for the magnetic head. However, although a dynamical method without the application of charge current directly has been gaining importance, its low efficiency is an issue. In this study, we explored possible materials to realize highly efficient spin injection and realized about 20 times higher efficient than previous study using single-crystalline Fe_3Si as a spin injector. Furthermore, we clarified a mechanism for the highly efficient spin injection.

  • Spin injection and transport in p-type Si induced by the spin-pumping at room temperature

    K. Kubo, E. Shikoh, K. Ando, E. Saitoh, T. Shinjo, M. Shiraishi

    111 ( 387. MR2011-36 ) 21 - 25 2012  [Refereed]  [Invited]

     View Summary

    Since the spin-orbit interaction in Si is essentially small due to the good crystalline symmetry, Si-based functional devices using the spin degree of freedom is recognized to be promising with respect to the spin coherence. Whereas spin transport at room temperature (RT) in n-type Si has been reported by using an electrical method, spin transport in p-type Si has not been experimentally realized, which is an important and unexplored milestone in spintronics. In this study, the spin transport in p-type Si at RT was demonstrated by using a dynamical method so-called spin-pumping.

  • Observation of weak temperature dependence of spin diffusion length in highly-doped Si by using a non-local 3-terminal method

    M. Kameno, E. Shikoh, T. Oikawa, T. Sasaki, T. Suzuki, Y. Suzuki, M. Shiraishi

    Journal of Applied Physics  111   07C322-1 - 07C322-3 2012  [Refereed]  [Invited]

     View Summary

    We conduct an experimental investigation of temperature dependence of spin diffusion length in highly doped n-type silicon by using a non-local 3-terminal method. Whereas an effect of spin drift is not negligible in non-metallic systems, it is not fully conclusive how the spin drift affects spin transport properties in highly doped Si in a non-local 3-terminal method. Here, we report on temperature dependence of spin diffusion length in the Si, and it is clarified that the spin transport is less affected by an external electric field.

  • Thermal Degradation of Single-Walled Carbon Nanotubes during Alcohol Catalytic Chemical Vapor Deposition Process

    M.A. Azam, M.A. Mohamed, E. Shikoh, A. Fujiwara

    Japanese Journal of Applied Physics  49   02BA04-01 - 02BA04-06 2010  [Refereed]  [Invited]

     View Summary

    We have grown single-walled carbon nanotubes (SWCNTs) from Co catalyst thin films using the alcohol catalytic chemical vapor deposition (CVD) method for different CVD processing times. The structural properties of the SWCNTs grown have been investigated by Raman spectroscopy with various laser excitations. The growth progressed up to t=20 min, but the Raman intensity of SWCNTs decreased with increasing CVD processing time. The quality of as-grown SWCNTs also decreased with increasing CVD processing times, similar to the trend for Raman intensity. Raman intensity analysis in the radial breathing mode region shows a relatively wide distribution for SWCNTs grown for all CVD processing times, owing to the variations in growth and burning rates with SWCNT diameter. In this paper, we suggest that Co catalyst poisoning and SWCNT burning occur when the CVD processing time is more than 20 min.

  • Fabrication and Characterization of Carbon Nanotube Field-Effect Transistors using Ferromagnetic Electrodes with Different Coercivity

    M.A. Mohamed, M.A. Azam, E. Shikoh, A. Fujiwara

    Japanese Journal of Applied Physics  49   02BD08-01 - 02BD08-04 2010  [Refereed]  [Invited]

     View Summary

    We have succeeded in fabricating source and drain structures of carbon nanotube field-effect transistors (FETs) using ferromagnetic electrodes with different coercive fields. The electrodes were successfully bridged with single-walled carbon nanotubes (SWNTs) by a direct growth method. We investigated the magnetic properties of electrodes and FET characteristics. The magnetic properties of the electrodes survived the chemical vapor deposition process at up to 800 °C, and were found to be qualitatively preserved even at growth times of 20 and 30 min. In addition, the devices showed good field-effect modulation in conductivity. This device structure could be applied to carbon nanotube spintronics devices fabricated by a direct growth method.

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Conference Activities & Talks 【 display / non-display

  • Spin transport in thermally-evaporated polyacene films and the derivative films induced by the spin-pumping

    Yuji Tanaka, Taisei Kono, Masahiro Yamamoto, Yoshio Teki, Hiroaki Tsujimoto, Eiji Shikoh

    2019 Annual Conference on Magnetism and Magnetic Materials (MMM 2019)  2019.11 

     View Summary

    Molecular materials are promising on the viewpoint of the spin transport because of their weak spin-orbit interaction. The spin transport in thermally-evaporated pentacene films at room temperature (RT) was achieved with the spin-pumping driven by the ferromagnetic resonance (FMR), although the spin transport mechanism was unclear. In this study, to clarify the mechanism, the spin transport in evaporated tetracene films and TIPS-pentacene films were tried by the spin-pumping. Since a tetracene molecule has less pai-electrons per molecule than pentacene, the spin transport mechanism can be considered on a viewpoint of the pai-electron number difference. A TIPS-pentacene, which is a pentacene-derivative molecule, was focused to investigate the spin transport mechanism from another viewpoint of the film crystallinity difference. Pd(10)/molecules(0 to 100)/Ni80Fe20(25 nm in thick) tri-layer samples were formed on SiO2 substrates by using EB deposition or thermal evaporation. To avoid breaking the samples during Ni80Fe20 depositions, the substrate temperature was kept under 270 K. When the FMR of the Ni80Fe20 is excited with an ESR system, a pure spin current is injected from the Ni80Fe20 layer into the Pd layer via the molecular film. Then, the spin current is converted to a charge current due to the inverse spin-Hall effect (ISHE) in the Pd layer and detected as an electromotive force. For a control experiment, samples with a Cu layer instead of the Pd layer were formed since Cu has weaker spin-orbit interaction than Pd. The spin transport in a tetracene film has not been achieved yet because it was hard to form continuous tetracene films by thermal evaporation due to the high saturated vapor pressure. On TIPS-pentacene samples with a Pd layer, output voltages were observed under the FMR of the Ni80Fe20 and the voltage sign was inverted at the magnetization reversal of the Ni80Fe20. Meanwhile, no output voltages from the TIPS-samples with a Cu layer were observed under the FMR of the Ni80Fe20. These indicate that the output voltage observed from the TIPS-samples with a Pd is due to the ISHE. That is, the spin transport in evaporated TIPS-pentacene films by the spin-pumping was achieved at RT.

  • Temperature dependence of electromotive forces in Ni80Fe20/VO2 bilayer junctions under the ferromagnetic resonance

    2019.09 

  • Spin transport properties in evaporated rigid molecular film by using spin-pumping

    2019.09 

  • ナノダイヤモンド量子温度計測のためのマイクロ波アンテナ集積化細胞培養ディッシュ(Microwave-antenna-integrated cell dishes for nanodiamond quantum thermometry)

    Oshimi Keisuke, Nishimura Yushi, Tanaka Masuaki, Shikoh Eiji, Fujiwara Masazumi, Teki Yoshio

    バイオイメージング  2019.09  日本バイオイメージング学会

  • Spin transport properties in thermally-evaporated polyacene films and TIPS-pentacene films investigated by the spin-pumping

    Eiji Shikoh  [Invited]

    the 6th Awaji International Workshop on “Electron Spin Science & Technology: Biological and Materials Science Oriented Applications” (6th AWEST 2019)  2019.06 

     View Summary

    We developed an evaluation method of the spin transport property in materials with ferromagnetic resonance (FMR), called as “the spin-pumping method” [1]. First, this method was developed to achieve the spin transport at room temperature (RT) in an inorganic semiconductor material, p-type Si in 2013 [1] and then applied for a lot of materials. The spin-pumping is a generation method of a pure spin current which is a flow of spin angular momenta [2]. In a “ferromagnetic metal (FM) / target material / paramagnetic metal (PM)” tri-layer junction, a spin-pump-induced pure spin current, JS, driven by the FMR of the FM layer (for example, Ni80Fe20) is generated in the target material. This JS is absorbed into the PM layer (for example, Pd), converted into a charge current due to the inverse spin-Hall effect (ISHE) in the PM layer [3], and detected as an electromotive force (EMF) via the sample resistance. Thus, if the EMF due to the ISHE in the PM is detected under the FMR of the FM, it is clear evidence for spin transport in the target material.
    In 2014, the spin transport in conductive polymer PBTTT films formed by a solution process was achieved at RT with the spin-pumping [4] and it was suggested that the polarons mainly carry spins in the PBTTT films. In 2015, we achieved the spin transport in thermally-evaporated pentacene films by using the spin-pumping [5], and its spin diffusion length and the spin current relaxation time were evaluated to be about 40 nm and 150 ns at RT, respectively [5, 6]. However, a question “what carries the spins in pentacene films?” has been remained because a pure pentacene film is basically an insulator.
    Recently, we tried the spin-pumping-induced spin transport at RT in thermally- evaporated tetracene films possessing less -electron numbers per a molecule than pentacene, and in TIPS-pentacene films having higher crystallinity than pentacene. For tetracene, the making of thermally-evaporated films has not been succeeded yet because of its high vapor pressure. Meanwhile, we successfully demonstrated the spin-pump-induced spin transport in evaporated TIPS-pentacene films at RT [7]. The detail will be discussed in the presentation.

    [1] E. Shikoh, M. Shiraishi, et al., Phys. Rev. Lett., 2013, 110, 127201-1 – 4.
    [2] S. Mizukami, Y. Ando, T. Miyazaki, Phys. Rev B, 2002, 66, 104413-1 – 9.
    [3] E. Saitoh, M. Ueda, H. Miyajima, G. Tatara, Appl. Phys. Lett., 2006, 88, 182509-1 – 3.
    [4] S. Watanabe, et al., Nat. Phys., 2014, 10, 308 – 313.
    [5] Y. Tani, Y. Teki, E. Shikoh, Appl. Phys. Lett., 2015, 107, 242406-1 – 4.
    [6] Y. Tani, T. Kondo, Y. Teki, E. Shikoh, Appl. Phys. Lett., 2017, 110, 032403-1 – 4.
    [7] Y. Tanaka, Y. Teki, E. Shikoh, IEEE Trans. on Magnetism, 2019, 55, 1400304-1 – 4.

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Charge of on-campus class subject 【 display / non-display

  • Smart Energy

    (2019) Graduate school, Special course