Faculty Profiles - TANIYAMA Tomoyasu

Papers - TANIYAMA Tomoyasu

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Ferromagnetic phase nucleation and its growth evolution in FeRh thin films Reviewed International journal

A. S. Komlev, D. Y. Karpenkov, D. A. Kiselev, T. S. Ilina, A. Chirkova, R. R. Gimaev, T. Usami, T. Taniyama, V. I. Zverev, N. S. Perov

J. Alloys and Comp. Vol. 874 page： 159924 2021.4

Temperature dependence of the effective Gilbert damping constant of FeRh thin films Reviewed International journal

T. Usami, M. Itoh, T. Taniyama

AIP Advances Vol. 11 ( 4 ) page： 045302 - 045302 2021.4

Shear-strain-mediated large nonvolatile tuning of ferromagnetic resonance by electric field in multiferroic heterostructures Reviewed

M. Zheng, T. Usami, T. Taniyama

NPG Asia Mater. Vol. 13 page： 7 2021.1

Electric-field tunable anisotropic magnetoresistance effect in an epitaxial Co2FeSi/BaTiO3 interfacial multiferroic system Reviewed

S. Yamada, Y. Teramoto, D. Matsumi, D. Kepaptsoglou, I. Azaceta, T. Murata, K. Kudo, V. K. Lazarov, T. Taniyama, K. Hamaya

Phys. Rev. Mater. Vol. 5 ( 1 ) page： 014412 2021.1

In-plane ferroelectricity and enhanced Curie temperature in perovskite BaTiO3 epitaxial thin films Reviewed

K. Komatsu, I. Suzuki, T. Aoki, Y. Hamasaki, S. Yasui, M. Itoh, T. Taniyama

Appl. Phys. Lett. Vol. 117 ( 7 ) page： 072902 2020.8

Epitaxial strain engineering of luminescent properties in ZnGa2O4:Mn thin films Reviewed

T. Dazai, S. Yasui, T. Taniyama, M. Itoh

Appl. Phys. Express Vol. 13 ( 8 ) page： 082004 2020.7

Bandgap tuning and optimization of green-emitting Zn2SnO4-Mg2SnO4:Mn2+ using combinatorial pulsed laser deposition Reviewed

T. Dazai, S. Yasui, T. Taniyama, M. Itoh

Ceram. Int. Vol. 46 ( 13 ) page： 21771 - 21774 2020.5

Switchable third ScFeO3 polar ferromagnet with YMnO3-type structure Reviewed

Y. Hamasaki, T. Katayama, S. Yasui, T. Shiraishi, A. Akama, T. Kiguchi, T. Taniyama, and M. Itoh

J. Mater. Chem. C Vol. 8 page： 4447 - 4452 2020.4

The effects of BaTiO<inf>3</inf> nanodots density support on epitaxial LiCoO<inf>2</inf> thin-film for high-speed rechargeability Reviewed International journal

Sou Yasuhara, Shintaro Yasui, Takashi Teranishi, Yumi Yoshikawa, Tomoyasu Taniyama, Mitsuru Itoh

Electrochem. Commun. Vol. 109 page： 106604 2019.12

Language：English Publishing type：Research paper (scientific journal)

© 2019 The Authors LiCoO2 (LCO) is one of the most promising cathode materials for Li ion batteries (LIBs). However, LCO shows a rate-limiting step of Li+ migration between electrode and electrolyte interfaces, requiring LIBs to be charged under low-current conditions. For next generation batteries, it will be necessary to meet the demand for a shorter charging-time. We investigated a support method for the LCO surface to improve high C-rate performance, and revealed that the Li+ intercalation/de-intercalation reaction into/from LCO was accelerated by the introduction of a BaTiO3-LCO-electrolyte interface (triple-phase interface; TPI), due to the electric field concentration near the TPI. In this report, we investigate the dependence of high C-rate performance on the density of surface BaTiO3 nanodots using epitaxial LiCoO2 thin films created via pulsed laser deposition (PLD). As the number of nanodots increased, so did discharge capacity at 50C, becoming saturated at surface coverage over 22%. However, at 100C, the discharge capacity decreased at surface coverage over 40%. These results indicate that coalescence of nanodots reduces not only the TPI length but also the electrochemically active range at quite high C-rate. Therefore, we infer that optimal surface coverage should be varied depending on the C-rate.

DOI： 10.1016/j.elecom.2019.106604

Web of Science

Scopus

The effect of relative permittivity of surface supporting materials for high-speed rechargeable LiCoO<inf>2</inf> cathode film Reviewed International journal

Sou Yasuhara, Shintaro Yasui, Takashi Teranishi, Yumi Yoshikawa, Tomoyasu Taniyama, Mitsuru Itoh

J. Power Sources Vol. 441 page： 227194 2019.11

Language：English Publishing type：Research paper (scientific journal)

© 2019 Elsevier B.V. We previously reported that the BaTiO3(BTO)-LiCoO2(LCO)-electrolyte triple-phase interface (TPI) could play an important role in C-rate enhancement, however, why this supporting material is effective for high performance remains unknown. We focus on the relative permittivity of supporting materials using finite element method calculations and experiments. Calculations revealed that the electric field near the TPI was reinforced as the relative permittivity of supporting materials increased. Experimentally, we prepared nanodots and micropads deposited on LCO thin film using BTO and CeO2 as supporting materials to evaluate electrochemical properties and SEI formation mechanisms, respectively. High C-rate performance was improved by the introduction of CeO2 and BTO nanodots; however, only the BTO nanodots deposited on LCO could work at 100C. In addition, SEI around the TPI was quite thin around CeO2 and BTO pads, although 10 and 300 nm SEI were observed at the non-pad area of CeO2 and BTO, respectively. This indicated that the Li+ motion between electrolyte and electrode could be accelerated depending on the relative permittivity of supporting materials. The low SEI around the TPI of both the CeO2 and BTO pads suggested that the main reactions of Li+ insertion/de-insertion into/from LCO might be dominant around the TPI area.

DOI： 10.1016/j.jpowsour.2019.227194

Web of Science

Scopus

Voltage-driven strain-induced coexistence of both volatile and non-volatile interfacial magnetoelectric behaviors in LSMO/PMN-PT (001) Invited Reviewed

S. P. Pati, T. Taniyama

J. Phys. D: Appl. Phys. Vol. 53 ( 5 ) page： 054003 2019.11

Compositional dependence of Gilbert damping constant of epitaxial Fe100-xRhx thin films Reviewed

T. Usami, M. Itoh, T. Taniyama

Appl. Phys. Lett. Vol. 115 ( 14 ) page： 142403 2019.10

Strain-induced reversible manipulation of orbital magnetic moments in Ni/Cu multilayers on ferroelectric BaTiO3 Reviewed International journal

Okabayashi, Jun, Miura, Yoshio, Taniyama, Tomoyasu

NPJ Quantum Mater. Vol. 4 ( 1 ) page： 21 2019.5

Language：English Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

Controlling magnetic anisotropy by orbital magnetic moments related to interfacial strains has considerable potential for the development of future devices using spins and orbitals. For the fundamental physics, the relationship between strain and orbital magnetic moment is still unknown, because there are few tools to probe changes of orbital magnetic moment. In this study, we developed an electric field (E)-induced X-ray magnetic circular dichroism (EXMCD) technique to apply E to a ferroelectric BaTiO3 substrate. We reversibly tuned the interfacial lattice constants of Ni/Cu multilayers on BaTiO3 using this technique. As the domain structures in BaTiO3 are modulated by E, EXMCD measurements reveal that the changes in the magnetic anisotropy of Ni/Cu films are induced through the modulation of orbital magnetic moments in Ni with magneto-elastic contributions. The strained Ni layer that induces the perpendicular magnetic anisotropy without E is released at E = 8 kV/cm, and in-plane magnetization also occurs. We observed that EXMCD measurements clarified the origin of the reversible changes in perpendicular magnetic anisotropy and established the relationship between macroscopic inverse magnetostriction effects and microscopic orbital moment anisotropy.

DOI： 10.1038/s41535-019-0159-y

Web of Science

Scopus

Other Link： http://orcid.org/0000-0003-3683-5416

Enhancement of Ultrahigh Rate Chargeability by Interfacial Nanodot BaTiO<sub>3</sub> Treatment on LiCoO<sub>2</sub> Cathode Thin Film Batteries.

Yasuhara S, Yasui S, Teranishi T, Chajima K, Yoshikawa Y, Majima Y, Taniyama T, Itoh M

Nano letters 2019.2

Growth of CuSbS2 single crystal as an environmentally friendly thermoelectric material Reviewed

A. Nagaoka, M. Takeuchi, K Yoshino, S Ikeda, S. Yasui, T. Taniyama, K. Nishioka

Phys. Status Solidi (a) Vol. 216 page： 1800861 2019.2

Ferroelectric and ferrimagnetic properties of ε-RhxFe21xO3 thin films International journal

S. Yasui, T. Katayama, T. Osakabe, Y. Hamasaki, T. Taniyama, M. Itoh

J. Ceram. Soc. Jpn. Vol. 127 ( 7 ) page： 474 - 477 2019.1

Magnetic properties of single crystal GaFeO3 Reviewed

K. Tachiyama, S. Yasui, B. N. A. Rao, T. Dazai, T. Usami, T. Taniyama, T. Katayama, Y. Hamasaki, J. Yu, H. He, H. Wang, M. Itoh

MRS Advances Vol. 4 ( 1 ) page： 61 - 66 2019

Effects of chalcogen composition on the thermoelectric properties in Cu2ZnSn(S1-xSex)(4) single crystals

Nagaoka Akira, Masuda Taizo, Yasui Shintaro, Taniyama Tomoyasu, Nose Yoshitaro

JAPANESE JOURNAL OF APPLIED PHYSICS Vol. 57 ( 10 ) 2018.10

The single-crystal multinary compound Cu2ZnSnS4 as an environmentally friendly high-performance thermoelectric material Reviewed International journal

Akira Nagaoka, Taizo Masuda, Shintaro Yasui, Tomoyasu Taniyama, Yoshitaro Nose

Appl. Phys. Express Vol. 11 ( 5 ) 2018.5

Language：English Publishing type：Research paper (scientific journal) Publisher：Japan Society of Applied Physics

We investigated the thermoelectric properties of high-quality p-type Cu2ZnSnS4 single crystals. This material showed two advantages: low thermal conductivity because of lattice scattering caused by the easily formed Cu/Zn disordered structure, and high conductivity because of high doping from changes to the composition. All samples showed a thermal conductivity of 3.0 W m%1 K%1 at 300 K, and the Cu-poor sample showed a conductivity of 7.5 S/cm at 300 K because of the high density of shallow-acceptor Cu vacancies. The figure of merit of the Cu-poor Cu2ZnSnS4 reached 0.2 at 400 K, which is 1.4–45 times higher than those of related compounds.

DOI： 10.7567/APEX.11.051203

Web of Science

Scopus

Other Link： http://orcid.org/0000-0003-3683-5416

Strain-mediated magnetic response in La0.67Sr0.33MnO3/SrTiO3/La0.67Sr0.33MnO3/BaTiO3 structure Reviewed

Swain Anupama, Komatsu Katsuyoshi, Itoh Mitsuru, Taniyama Tomoyasu, Gorige Venkataiah

AIP ADVANCES Vol. 8 ( 5 ) 2018.5

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Papers - TANIYAMA Tomoyasu