論文

• Millimeter-Sized Epitaxial Ferroelectric BaTiO3 Freestanding Sheets Peeled from Al2O3 Substrates
  Weikun Zhou, Diwen Chen, Ren Mitsuya, Hiromichi Ohta, Tsukasa Katayama
  ACS Applied Electronic Materials, 2025年05月27日
  研究論文（学術雑誌）
• Antiferroelectric Behavior in Mixed‐Anion Bi2TiO4F2 Induced by Rotation of TiO3F3 Octahedra
  Tsukasa Katayama, Akira Chikamatsu, Motoaki Hirayama
  Advanced Functional Materials, 2025年04月21日
  研究論文（学術雑誌）
• Atomic Layer Deposition of Hafnium–Zirconium-Oxide Films Using a Liquid Cocktail Precursor Containing Hf(dmap)4 and Zr(dmap)4 for Ferroelectric Devices
  Akihiro Nishida, Tsukasa Katayama, Takashi Endo, Yasutaka Matsuo
  ACS Applied Materials & Interfaces, 2025年02月19日
  研究論文（学術雑誌）
• Water-soluble CaO sacrificial layer heteroepitaxially grown on yttria-stabilized zirconia substrate for large ferroelectric BaTiO3 sheets
  Weikun Zhou, Lizhikun Gong, Ren Mitsuya, Diwen Chen, Hiromichi Ohta, Tsukasa Katayama
  Journal of Materials Chemistry C, 2025年, ［査読有り］
  英語, 研究論文（学術雑誌）
• Topochemical Fluorination of Epitaxial Thin Films of Barium-Doped Bismuth Iron Oxyfluoride
  Mizuho Sano, Akiko Kamigaito, Yusuke Wakayama, Kei Shigematsu, Tsukasa Katayama, Yasushi Hirose, Akira Chikamatsu
  Crystal Growth & Design, 24, 22, 9344, 9349, American Chemical Society (ACS), 2024年11月07日
  研究論文（学術雑誌）
• Ferroelectric BaTiO3 Freestanding Sheets for an Ultra-High-Speed Light-Driven Actuator
  Lizhikun Gong, Atsushi Taguchi, Weikun Zhou, Ren Mitsuya, Hiromichi Ohta, Tsukasa Katayama
  ACS Applied Materials & Interfaces, 2024年10月09日
  研究論文（学術雑誌）
• Unusual Crystal Orientation in Hexagonal HoFeO3 Multiferroic Films and the Effect on Magnetism
  Binjie Chen, Jinghuang Lin, Bin Feng, Yuichi Ikuhara, Hiromichi Ohta, Tsukasa Katayama
  Crystal Growth & Design, 2024年10月03日
  研究論文（学術雑誌）
• High-concentration doping effects of aliovalent Al and Ga on ferroelectric properties of BaTiO3 Films
  Ko Marunouchi, Lizhikun Gong, Hiromichi Ohta, Tsukasa Katayama
  Thin Solid Films, 796, 140339, 140339, Elsevier BV, 2024年05月
  研究論文（学術雑誌）
• Magnetic Phase Transition-Induced Modulation of Ferroelectric Properties in Hexagonal RFeO₃ (R = Tb and Ho)
  Yaoming Liu, Binjie Chen, Yosuke Hamasaki, Lizhikun Gong, Hiromichi Ohta, Tsukasa Katayama
  ACS Applied Materials & Interfaces, 16, 14, 17832, 17837, American Chemical Society (ACS), 2024年04月01日
  研究論文（学術雑誌）
• Cation-placement control in double-perovskite GdBaCo₂O₆ and its impact on magnetism via spin-state modification
  Tsukasa Katayama, Kento Magara, Shiro Sakai, Yijie Zeng, Akira Chikamatsu, Tetsuya Hasegawa
  Journal of Materials Chemistry C, 12, 28, 10428, 10436, Royal Society of Chemistry (RSC), 2024年
  研究論文（学術雑誌）, A-site-ordered and -disordered GdBaCo₂O₆ films were synthesized through topotactic oxidation. These films exhibit distinct magnetic and conductive properties, attributed to variations in Co spin states driven by changes in ionic arrangement.
• Large tensile-strained BaTiO3 films grown on lattice-mismatched La-doped BaSnO3 bottom electrode
  Lizhikun Gong, Ko Marunouchi, Akira Chikamatsu, Hiromichi Ohta, Tsukasa Katayama
  CrystEngComm, Royal Society of Chemistry (RSC), 2024年
  研究論文（学術雑誌）, Perovskite BaTiO3 has been widely studied and utilized in various applications owing to its high permittivity, ferroelectricity, non-toxicity, and stability. However, its low ferroelectric-paraelectric phase transition temperature (TC, 120 °C)...
• Ferroelectricity, High Permittivity, and Tunability in Millimeter-Size Crack-Free Ba_1-xSr_xTiO₃ Flexible Epitaxial Sheets
  Yu, R., Gong, L., Ohta, H., Katayama, T.
  ACS Applied Electronic Materials, 5, 9, 2023年09月26日
  研究論文（学術雑誌）
• Atomic Layer Deposition of HfO₂ Films Using Tetrakis(1-(N,N-dimethylamino)-2-propoxy)hafnium [Hf(dmap)₄] for Advanced Gate Dielectrics Applications
  Akihiro Nishida, Tsukasa Katayama, Yasutaka Matsuo
  ACS Applied Nano Materials, American Chemical Society (ACS), 2023年09月15日
  研究論文（学術雑誌）
• Anisotropic proton conduction in double-perovskite GdBaCo₂O_5.5
  Katayama, T., Magara, K., Chikamatsu, A., Hasegawa, T.
  Applied Physics Letters, 123, 1, 2023年07月03日
  研究論文（学術雑誌）
• Solid phase epitaxy of perpendicular magnetic BaFe₁₂O₁₉ flexible sheets on a mica substrate
  Tsukasa Katayama, Shishin Mo, Akira Chikamatsu, Tetsuya Hasegawa
  Japanese Journal of Applied Physics, 62, 6, 065505, 065505, IOP Publishing, 2023年06月01日
  研究論文（学術雑誌）, Abstract
  
  Epitaxial M-type BaFe₁₂O₁₉ flexible sheets, exhibiting RT perpendicular magnetization, were synthesized on mica substrates through the solid phase epitaxy method. The [110] and [001] directions of the BaFe₁₂O₁₉ layer were parallel to the [010] and [001] directions of the mica, respectively. In the synthesis process, amorphous BaFe₁₂O₁₉ films were firstly prepared on Al₂O₃-buffered mica (001) substrates and then annealed at 800 °C–900 °C in air for single crystallization. During optimization of the synthesis, we found that preparation of the buffer layer and controlling annealing temperature are important for obtaining the epitaxial sheet. The sheets exhibited perpendicular ferrimagnetism with large saturated magnetization (60 Am² kg⁻¹) and magnetic anisotropy coefficient (2.1 × 10⁵ J m⁻³) at 300 K, together with flexibility.
• Half-Metallicity and Magnetic Anisotropy in Double-Perovskite GdBaCo₂O₆ Films Prepared via Topotactic Oxidation
  Tsukasa Katayama, Shishin Mo, Akira Chikamatsu, Yuji Kurauchi, Hiroshi Kumigashira, Tetsuya Hasegawa
  Chemistry of Materials, American Chemical Society (ACS), 2023年01月18日
  研究論文（学術雑誌）
• Atomic layer deposition of Y₂O₃ films using a novel liquid homoleptic yttrium precursor tris(sec-butylcyclopentadienyl)yttrium [Y(^sBuCp)₃] and water
  Akihiro Nishida, Tsukasa Katayama, Yasutaka Matsuo
  RSC Advances, 13, 39, 27255, 27261, Royal Society of Chemistry (RSC), 2023年, ［査読有り］
  研究論文（学術雑誌）, Atomic layer deposition of Y₂O₃ films was demonstrated using a novel liquid homoleptic yttrium precursor Y(^sBuCp)₃ and water. The deposited Y₂O₃ films exhibit high purity, high crystallinity, a smooth surface, and high electronic performance.
• Grain engineered polar-axis-oriented epitaxial Mn₂Mo₃O₈ films with enhanced magnetic transition temperature
  Shishin Mo, Tsukasa Katayama, Akira Chikamatsu, Tetsuya Hasegawa
  Journal of Materials Chemistry C, Royal Society of Chemistry (RSC), 2023年
  研究論文（学術雑誌）, Magnetic transition temperature of polar-axis-oriented Mn₂Mo₃O₈ epitaxial films was enhanced by grain engineering.
• Synthesis and transparent conductivity of crack-free La:BaSnO₃ epitaxial flexible sheets
  Lizhikun Gong, Rui Yu, Hiromichi Ohta, Tsukasa Katayama
  Dalton Transactions, Royal Society of Chemistry (RSC), 2023年
  研究論文（学術雑誌）, La-doped BaSnO₃ (LBSO), which exhibits both high electron mobility and visible-light transparency, is a promising transparent electrode/transistor material that does not require expensive elements such as indium.
• Hexagonal RFeO₃ (R = Dy, Er, and Lu) Films Grown on Glass Substrates with Both Magnetic and Ferroelectric Orders
  Chen, B., Katayama, T.
  ACS Applied Electronic Materials, 5, 1, 2023年
  研究論文（学術雑誌）
• Significant Suppression of Cracks in Freestanding Perovskite Oxide Flexible Sheets Using a Capping Oxide Layer
  Gong, L., Wei, M., Yu, R., Ohta, H., Katayama, T.
  ACS Nano, 16, 12, 2022年12月27日
  研究論文（学術雑誌）
• Photo-induced antiferromagnetic-ferromagnetic and spin-state transition in a double-perovskite cobalt oxide thin film
  Yujun Zhang, Tsukasa Katayama, Akira Chikamatsu, Christian Schü{\ss}ler-Langeheine, Niko Pontius, Yasuyuki Hirata, Kou Takubo, Kohei Yamagami, Keisuke Ikeda, Kohei Yamamoto, Tetsuya Hasegawa, Hiroki Wadati
  Communications Physics, 5, 1, Springer Science and Business Media {LLC}, 2022年12月
  英語, 研究論文（学術雑誌）, AbstractInvestigation of ultrafast dynamic behaviors can provide novel insights about the coupling mechanisms among multiple degrees of freedom in condensed matters, such as lattice, magnetism and electronic structure. Here we investigate both the ferromagnetic (FM) and antiferromagnetic (AFM) dynamics of a strongly correlated oxide system, GdBaCo2O5.5 thin film by time-resolved x-ray magnetic circular dichroism in reflectivity (XMCDR) and resonant magnetic x-ray diffraction (RMXD). A photo-induced AFM-FM transition characterized by an increase of the transient XMCDR (sensitive to FM order) beyond the unpumped value and a decay of RMXD (sensitive to AFM order) was observed. The photon-energy dependence of the transient XMCDR and reflectivity could be interpreted as a concomitant photo-induced spin-state transition (SST). The AFM-FM transition and SST couple with each other in the time domain, resulting in unusual dynamic behaviors of the magnetism.
• Epitaxial growth of hexagonal GdFeO3 thin films with magnetic order by pulsed laser deposition
  Jun Kasahara, Tsukasa Katayama, Akira Chikamatsu, Yosuke Hamasaki, Tetsuya Hasegawa
  Thin Solid Films, 757, 139409, 139409, Elsevier BV, 2022年09月
  研究論文（学術雑誌）
• Ferroelectric and Magnetic Properties of Hexagonal ErFeO₃Epitaxial Films
  Chen, B., Ohta, H., Katayama, T.
  ACS Applied Electronic Materials, 4, 9, American Chemical Society (ACS), 2022年08月23日
  研究論文（学術雑誌）
• Ionic order and magnetic properties of double-perovskite GdBaCo₂O_5.5 films on SrTiO₃ substrates
  Tsukasa Katayama, Akira Chikamatsu, Tetsuya Hasegawa
  Journal of the Ceramic Society of Japan, 130, 7, 429, 431, Ceramic Society of Japan, 2022年07月01日
  英語, 研究論文（学術雑誌）
• Enhancement of room-temperature magnetization in GaFeO₃-type single crystals by Al and Sc doping
  Wang, L., Katayama, T., Wang, C., Li, Q., Shi, Y., Fang, Y., Huang, F., Zhu, Y., Li, H.-F., Yasui, S., Huang, X., Yu, J.
  AIP Advances, 12, 6, 065015, 065015, AIP Publishing, 2022年06月01日
  研究論文（学術雑誌）
• Crystal structure and electronic property modification of Ca2RuO4 thin films via fluorine doping
  Shota Fukuma, Akira Chikamatsu, Tsukasa Katayama, Takahiro Maruyama, Keiichi Yanagisawa, Koji Kimoto, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Yasushi Hirose, Tetsuya Hasegawa
  Physical Review Materials, 6, 3, 2022年03月23日
  英語, 研究論文（学術雑誌）
• Negative magnetoresistance in different nitrogen content EuNbO_3−xN_x single-crystalline thin films
  Maruyama, T., Hirose, Y., Katayama, T., Sugisawa, Y., Sekiba, D., Hasegawa, T., Chikamatsu, A.
  Journal of Materials Chemistry C, 10, 39, Royal Society of Chemistry (RSC), 2022年
  研究論文（学術雑誌）
• Antiferroelectric-to-ferroelectric phase transition in hexagonal rare-earth iron oxides
  Chen, B., Hasegawa, T., Ohta, H., Katayama, T.
  Journal of Materials Chemistry C, 10, 14, 5621, 5626, Royal Society of Chemistry ({RSC}), 2022年
  研究論文（学術雑誌）
• Improvement of electric insulation in dielectric layered perovskite nickelate films via fluorination
  Takuma Nishimura, Tsukasa Katayama, Shishin Mo, Akira Chikamatsu, Tetsuya Hasegawa
  Journal of Materials Chemistry C, Royal Society of Chemistry ({RSC}), 2022年
  研究論文（学術雑誌）, Epitaxial films of La_3/2Sr_1/2NiO_xF_y with a wide range of fluorine content (y), 0.4–3, were prepared. The fluorinated film exhibited high electric insulation due to the large and random bond distortions provided by the fluorination.
• Ferroelectric and magnetic properties in ε-Fe2O3 epitaxial film
  Yosuke Hamasaki, Shintaro Yasui, Tsukasa Katayama, Takanori Kiguchi, Shinya Sawai, Mitsuru Itoh
  Applied Physics Letters, 119, 18, 182904, 182904, AIP Publishing, 2021年11月01日
  研究論文（学術雑誌）
• Epitaxial-Strain-Induced Spontaneous Magnetization in Polar Mn2Mo3O8
  Shishin Mo, Tsukasa Katayama, Akira Chikamatsu, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Tetsuya Hasegawa
  Chemistry of Materials, 33, 19, 7713, 7718, American Chemical Society ({ACS}), 2021年10月12日
  研究論文（学術雑誌）
• Single-Crystal Synthesis of ϵ-Fe₂O₃-Type Oxides Exhibiting Room-Temperature Ferrimagnetism and Ferroelectric Polarization
  Zhang, Y., Wang, H., Tachiyama, K., Katayama, T., Zhu, Y., Wu, S., Li, H.-F., Fang, J., Li, Q., Shi, Y., Wang, L., Fu, Z., Xu, F., Yu, J., Yasui, S., Itoh, M.
  Crystal Growth and Design, 21, 9, American Chemical Society ({ACS}), 2021年07月29日
  研究論文（学術雑誌）
• Ionic Order Engineering in Double-Perovskite Cobaltite
  Tsukasa Katayama, Akira Chikamatsu, Yujun Zhang, Shintaro Yasui, Hiroki Wadati, Tetsuya Hasegawa
  Chemistry of Materials, 33, 14, 5675, 5680, American Chemical Society ({ACS}), 2021年07月27日
  研究論文（学術雑誌）
• Synthesis and magnetism of MoCo2O4 spinel thin films
  Tsukasa Katayama, Shishin Mo, Yuji Kurauchi, Akira Chikamatsu, Tetsuya Hasegawa
  Thin Solid Films, 728, 138696, 138696, Elsevier {BV}, 2021年06月
  研究論文（学術雑誌）
• Room-Temperature Antiferroelectricity in Multiferroic Hexagonal Rare-Earth Ferrites
  Jun Kasahara, Tsukasa Katayama, Shishin Mo, Akira Chikamatsu, Yosuke Hamasaki, Shintaro Yasui, Mitsuru Itoh, Tetsuya Hasegawa
  ACS Applied Materials & Interfaces, 13, 3, 4230, 4235, American Chemical Society ({ACS}), 2021年01月27日, ［国際誌］
  英語, 研究論文（学術雑誌）, The antiferroelectric (AFE) phase, in which nonpolar and polar states are switchable by an electric field, is a recent discovery in promising multiferroics of hexagonal rare-earth manganites (ferrites), h-RMn(Fe)O3. However, this phase has so far only been observed at 60-160 K, which restricts key investigations into the microstructures and magnetoelectric behaviors. Herein, we report the successful expansion of the AFE temperature range (10-300 K) by preparing h-DyFeO3 films through epitaxial stabilization. Room-temperature scanning transmission electron microscopy reveals that the AFE phase originates from a nanomosaic structure comprising AFE P3̅c1 and ferroelectric P63cm domains with small domain sizes of 1-10 nm. The nanomosaic structure is stabilized by a low c/a ratio derived from the large ionic radius of Dy3+. Furthermore, weak ferromagnetism and magnetocapacitance behaviors are observed. Below 10 K, the film exhibits an M-shaped magnetocapacitance versus magnetic field curve, indicating unusual magnetoelectric coupling in the AFE phase.
• Large Polarization Switching and High-Temperature Magnetoelectric Coupling in Multiferroic GaFeO3 Systems
  Hui Wang, Yang Zhang, Koki Tachiyama, Zhaoyang Xia, Jinghong Fang, Qin Li, Guofeng Cheng, Yun Shi, Ji, ing Yu, Tsukasa Katayama, Shintaro Yasui, Mitsuru Itoh
  Inorganic Chemistry, 60, 1, 225, 230, 2021年01月04日
  英語, 研究論文（学術雑誌）
• Investigation of the electronic states of A-site layer-ordered double perovskite YBaCo2Ox (x = 5.3 and 6) thin films by x-ray spectroscopy
  Akira Chikamatsu, Tsukasa Katayama, Takahiro Maruyama, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Hiroki Wadati, Tetsuya Hasegawa
  Applied Physics Letters, 118, 1, 012401, 012401, {AIP} Publishing, 2021年01月04日
  研究論文（学術雑誌）
• Simple Method to Obtain Large‐Size Single‐Crystalline Oxide Sheets
  Ke Gu, Tsukasa Katayama, Shintaro Yasui, Akira Chikamatsu, Sou Yasuhara, Mitsuru Itoh, Tetsuya Hasegawa
  Advanced Functional Materials, 30, 28, 2001236, 2001236, Wiley, 2020年07月25日
  研究論文（学術雑誌）
• Modulating the Structure and Magnetic Properties of ε-Fe2O3 Nanoparticles via Electrochemical Li+ Insertion
  Tsukasa Katayama
  Inorganic Chemistry, 59, 7, 4357, 4365, 2020年04月06日
  英語, 研究論文（学術雑誌）
• Redox-based multilevel resistive switching in AlFeO3 thin-film heterostructures
  Tsukasa Katayama
  ACS Applied Electronic Materials, 2, 4, 1065, 1073, American Chemical Society (ACS), 2020年03月29日
  英語, 研究論文（学術雑誌）
• 六方晶GdFeO₃マルチフェロイック薄膜の合成
  笠原 淳, 片山 司, 毛 司辰, 近松 彰, 安井 伸太郎, 伊藤 満, 長谷川 哲也
  応用物理学会学術講演会講演予稿集, 2020.1, 1354, 1354, 公益社団法人 応用物理学会, 2020年02月28日
  日本語
• Electronic properties of perovskite strontium chromium oxyfluoride epitaxial thin films fabricated via low-temperature topotactic reaction
  Akira Chikamatsu, Takahiro Maruyama, Tsukasa Katayama, Yu Su, Yoshihiro Tsujimoto, Kazunari Yamaura, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Tetsuya Hasegawa
  Physical Review Materials, 4, 2, 2020年02月18日
  研究論文（学術雑誌）
• Switchable third ScFeO3 polar ferromagnet with YMnO3-type structure
  Yosuke Hamasaki, Tsukasa Katayama, Shintaro Yasui, Takahisa Shiraishi, Akihiro Akama, Takanori Kiguchi, Tomoyasu Taniyama, Mitsuru Itoh
  Journal of Materials Chemistry C, 8, 13, 4447, 4452, Royal Society of Chemistry ({RSC}), 2020年
  研究論文（学術雑誌）,

  We prepared a third ScFeO₃ polar ferromagnet with YMnO₃-type structure using a heteroepitaxial film technique and characterized its physical properties.

• Influence of fluorination on electronic states and electron transport properties of Sr2IrO4 thin films
  Takahiro Maruyama, Akira Chikamatsu, Tsukasa Katayama, Kenta Kuramochi, Hiraku Ogino, Miho Kitamura, Koji Horiba, Hiroshi Kumigashira, Tetsuya Hasegawa
  Journal of Materials Chemistry C, 8, 24, 8268, 8274, Royal Society of Chemistry ({RSC}), 2020年
  研究論文（学術雑誌）
• Investigation of ferrimagnetism and ferroelectricity in AlxFe2−xO3 thin films
  Badari Narayana Rao, Shintaro Yasui, Tsukasa Katayama, Ayako Taguchi, Hiroki Moriwake, Yosuke Hamasaki, Mitsuru Itoh
  Journal of Materials Chemistry C, 8, 2, 706, 714, 2020年
  英語, 研究論文（学術雑誌）
• Two-Dimensional Fluorine Distribution in a Heavily Distorted Perovskite Nickel Oxyfluoride Revealed by First-Principles Calculation
  Kurauchi, Y., Katayama, T., Chikamatsu, A., Hasegawa, T.
  Journal of Physical Chemistry C, 123, 51, 31190, 31195, American Chemical Society ({ACS}), 2019年12月26日
  研究論文（学術雑誌）
• Theoretical Investigation of the Role of the Nitride Ion in the Magnetism of Oxynitride MnTaO₂N
  Mo, S., Kurauchi, Y., Katayama, T., Hirose, Y., Hasegawa, T.
  Journal of Physical Chemistry C, 123, 41, 25379, 25384, American Chemical Society ({ACS}), 2019年10月17日
  研究論文（学術雑誌）
• Ferroelectric and ferrimagnetic properties of ε-RhxFe2−xO3 thin films
  Tsukasa Katayama
  Journal of the Ceramic Society of Japan, 127, 7, 474, 477, 2019年07月01日
  英語, 研究論文（学術雑誌）
• Improved crystalline quality and electric conductivity in infinite-layer SrFeO₂ films through Sm substitution
  Katayama, T., Chikamatsu, A., Kumigashira, H., Hasegawa, T.
  Applied Physics Letters, 114, 23, 2019年06月10日
  研究論文（学術雑誌）
• P-Type Conductivity and Room-Temperature Ferrimagnetism in Spinel MoFe ₂ O ₄ Epitaxial Thin Film
  Katayama, T., Kurauchi, Y., Mo, S., Gu, K., Chikamatsu, A., Galiullina, L., Hasegawa, T.
  Crystal Growth and Design, 19, 2, 902, 906, American Chemical Society ({ACS}), 2019年02月06日
  研究論文（学術雑誌）
• Selective fluorination of perovskite iron oxide/ruthenium oxide heterostructures: Via a topotactic reaction
  Chikamatsu, A., Suzuki, Y., Maruyama, T., Onozuka, T., Katayama, T., Ogawa, D., Hasegawa, T.
  Chemical Communications, 55, 17, Royal Society of Chemistry ({RSC}), 2019年
  研究論文（学術雑誌）
• Fabrication and Characterization of Multiferroic Al0.5Fe1.5O3 Epitaxial Thin Films
  Tsukasa Katayama
  MRS Advances, 4, 9, 539, 544, Springer Science and Business Media LLC, 2019年
  英語, 研究論文（学術雑誌）, ABSTRACTSingle-phase multiferroic materials have attracted considerable attention among scientists, due to the strong drive in industry towards device miniaturization, addition of new functionalities, etc. Currently, most of the discovered materials have at-least one ferroic order active only at low temperatures, thereby hindering their induction into practical devices. κ-Al2O3-type AlxFe2-xO3 (x-AFO) oxides belong to a new class of metastable multiferroic compounds (space group: Pna21), with relatively high Curie temperatures. The current work investigates the effect of thin film deposition conditions on the ferroelectric and ferrimagnetic properties of Al0.5Fe1.5O3 (0.5-AFO). Substrate temperature and oxygen partial pressure during deposition were found to be the critical parameters in obtaining high quality films. Optimizing the deposition conditions of 0.5-AFO enabled observation of both ferroelectricity and ferrimagnetism at room temperature.
• Magnetic properties of Single Crystal GaFeO3
  Tsukasa Katayama
  MRS Advances, 4, 1, 61, 66, Springer Science and Business Media LLC, 2019年
  英語, 研究論文（学術雑誌）, Abstractκ-Al2O3-type GaFeO3 is a promising multiferroic material due to the coexistence of a large spontaneous magnetization and polarization near room temperature. In the current study, we present the magnetic properties of single crystalline GaFeO3 and compare it with that of ε-Fe2O3. Magnetic measurements revealed that spontaneous magnetization appears below 540 K in two steps, similar to that reported for ε−Fe2O3. Partial magnetic ordering takes place at 540 K (TN1), with Fe3+ ions in two distorted octahedral sites ordering antiparallel to one another. Upon further cooling at 200 K (TN2), the remaining Fe3+ ions in regular octahedra and tetrahedra order antiparallel to one another. Substitution of Ga for Fe in ε-Fe2O3 leads to a decrease in TN1 and TN2 from 850 to 540 K and from 480 to 200 K, respectively, caused by a dilution of magnetic Fe by nonmagnetic Ga and preferential site occupation of Ga.
• Reactive solid phase epitaxy of layered aurivillius-type oxyfluorides Bi ₂ TiO ₄ F ₂ using polyvinylidene fluoride
  Katayama, T., Mo, S., Maruyama, T., Chikamatsu, A., Hasegawa, T.
  Dalton Transactions, 48, 16, Royal Society of Chemistry ({RSC}), 2019年
  研究論文（学術雑誌）
• Epitaxial Growth of Orthorhombic GaFeO₃ Thin Films on SrTiO₃ (111) Substrates by Simple Sol-Gel Method.
  Zhang, Minghui, Yasui, Shintaro, Katayama, Tsukasa, Rao, Badari Narayana, Wen, Haiqin, Pan, Xiuhong, Tang, Meibo, Ai, Fei, Itoh, Mitsuru
  Materials (Basel, Switzerland), 12, 2, 2019年, ［国際誌］
  英語, 研究論文（学術雑誌）, A Sol-gel method assisted with spin-coating has been successfully used to grow orthorhombic GaFeO₃ epitaxial films on SrTiO₃ (111) substrates for the first time. The film with Pna2₁ crystal structure has been grown along the c-axis. The rocking curve of (004) reflection shows that the Full-Width at Half-Maximum (FWHM) value could be determined to be 0.230°, indicating good single crystallinity and high quality. X-ray Φ scan reveals a three-fold symmetry of the substrate and a six-fold symmetry of the film, respectively. The in-plane domains rotate 60° from each other in the film. Uniform film with dense structure, columnar grains with similar grain size was obtained. The thickness of the film was evaluated to be ~170 nm. The roughness value (RMS) measured by AFM was 4.5 nm, revealing a flat film. The in-plane Magnetization versus Magnetic field (M-H) curve at 5 K performs a typical ferri- or ferromagnetic hysteresis loop with a saturated magnetization (Ms) value of 136 emu/cm³. The Curie temperature could be determined to be 174 K. Compared to Pulsed Laser Deposition (PLD), the sol-gel method can prepare large area films with low cost. These new films show promising applications in multiferroic devices.
• 単結晶SrRuO₃シートの合成
  Gu Ke, 片山 司, 安井 伸太郎, 近松 彰, 伊藤 満, 長谷川 哲也
  応用物理学会学術講演会講演予稿集, 2018.2, 1505, 1505, 公益社団法人 応用物理学会, 2018年09月05日
  日本語
• Ferroelectric and Magnetic Properties in Room-Temperature Multiferroic Ga_xFe_2−xO₃ Epitaxial Thin Films
  Katayama, T., Yasui, S., Hamasaki, Y., Shiraishi, T., Akama, A., Kiguchi, T., Itoh, M.
  Advanced Functional Materials, 28, 2, 1704789, 1704789, Wiley-Blackwell, 2018年01月27日
  研究論文（学術雑誌）
• Fabrication of Fluorite-Type Fluoride Ba_0.5Bi_0.5F_2.5 Thin Films by Fluorination of Perovskite BaBiO₃ Precursors with Poly(vinylidene fluoride)
  Chikamatsu, A., Kawahara, K., Shiina, T., Onozuka, T., Katayama, T., Hasegawa, T.
  ACS Omega, 3, 10, 2018年
  研究論文（学術雑誌）
• Effect of Cr substitution on ferrimagnetic and ferroelectric properties of GaFeO3 epitaxial thin films
  Katayama, Tsukasa, Osakabe, Takuya, Yasui, Shintaro, Hamasaki, Yosuke, Rao, Badari Narayana, Zhang, Minghui, Itoh, Mitsuru
  Applied Physics Letters, 113, 16, 162901, 162901, 2018年
  研究論文（学術雑誌）
• Ferromagnetism with strong magnetocrystalline anisotropy in A-site ordered perovskite YBaCo2O6 epitaxial thin films prepared via wet-chemical topotactic oxidation
  Katayama, Tsukasa, Chikamatsu, Akira, Hirose, Yasushi, Minohara, Makoto, Kumigashira, Hiroshi, Harayama, Isao, Sekiba, Daiichiro, Hasegawa, Tetsuya
  Journal of Materials Chemistry C, 6, 13, 3445, 3450, 2018年
  英語, 研究論文（学術雑誌）
• Ferrimagnetism and Ferroelectricity in Cr-Substituted GaFeO3 Epitaxial Films
  Tsukasa Katayama, Shintaro Yasui, Takuya Osakabe, Yosuke Hamasaki, Mitsuru Itoh
  Chemistry of Materials, 30, 4, 1436, 1441, 2018年
  研究論文（学術雑誌）
• Epitaxial thin film growth of garnet-, GdFeO3-, and YMnO3-type LuFeO3 using pulsed laser deposition
  Tsukasa Katayama, Yosuke Hamasaki, Shintaro Yasui, Akiko Miyahara, Mitsuru Itoh
  Thin Solid Films, 642, 41, 44, Elsevier {BV}, 2017年11月
  研究論文（学術雑誌）
• κ-アルミナ型酸化物強誘電体の構造と強誘電性
  伊藤 満, 片山 司, 安井 伸太郎, 谷山 智康, 森分 博紀, 小西 綾子, 木口 賢紀, 白石 貴久, 赤間 章裕, 濱嵜 容丞
  日本物理学会講演概要集, 72.2, 2321, 2321, 一般社団法人 日本物理学会, 2017年
  日本語
• Electric Transport Characteristics of Gallium Iron Oxide Epitaxial Thin Film
  Katayama, Tsukasa, Yasui, Shintaro, Hamasaki, Yosuke, Itoh, Mitsuru
  Mrs Advances, 2, 56, 2017年
  研究論文（学術雑誌）
• Topotactic fluorination of perovskite strontium ruthenate thin films using polyvinylidene fluoride
  Kawahara, K., Chikamatsu, A., Katayama, T., Onozuka, T., Ogawa, D., Morikawa, K., Ikenaga, E., Hirose, Y., Harayama, I., Sekiba, D., Fukumura, T., Hasegawa, T.
  Crystengcomm, 19, 2, 313, 317, 2017年
  研究論文（学術雑誌）
• Reversible Changes in Resistance of Perovskite Nickelate NdNiO3 Thin Films Induced by Fluorine Substitution
  Onozuka, Tomoya, Chikamatsu, Akira, Katayama, Tsukasa, Hirose, Yasushi, Harayama, Isao, Sekiba, Daiichiro, Ikenaga, Eiji, Minohara, Makoto, Kumigashira, Hiroshi, Hasegawa, Tetsuya
  Acs Applied Materials & Interfaces, 9, 12, 10882, 10887, 2017年
  英語, 研究論文（学術雑誌）
• First-Principles Calculations on the Crystal/Electronic Structure and Phase Stability of H-Doped SrFeO₂
  Kurauchi, Y., Kamisaka, H., Katayama, T., Chikamatsu, A., Hasegawa, T.
  Journal of Physical Chemistry C, 121, 13, 2017年
  研究論文（学術雑誌）
• Control of crystal-domain orientation in multiferroic Ga_0.6Fe_1.4O₃ epitaxial thin films
  Katayama, T., Yasui, S., Hamasaki, Y., Itoh, M.
  Applied Physics Letters, 110, 21, 2017年
  研究論文（学術雑誌）
• Chemical tuning of roomerature ferrimagnetism and ferroelectricity in ϵ-Fe₂O₃-type multiferroic oxide thin films
  Katayama, T., Yasui, S., Hamasaki, Y., Osakabe, T., Itoh, M.
  Journal of Materials Chemistry C, 5, 47, 2017年
  研究論文（学術雑誌）
• Topotactic reductive synthesis of A-site cation-ordered perovskite YBaCo
  Katayama Tsukasa, Chikamatsu Akira, Fukumura Tomoteru, Hasegawa Tetsuya
  Jpn. J. Appl. Phys., 55, 4, 04EJ05, 2016年
  英語, 研究論文（学術雑誌）
• Formation of defect-fluorite structured NdNiO: _XH_y epitaxial thin films via a soft chemical route from NdNiO₃ precursors
  Onozuka, T., Chikamatsu, A., Katayama, T., Fukumura, T., Hasegawa, T.
  Dalton Transactions, 45, 30, 2016年
  研究論文（学術雑誌）
• Experimental and theoretical investigation of electronic structure of SrFeO
  Katayama Tsukasa, Chikamatsu Akira, Kamisaka Hideyuki, Kumigashira Hiroshi, Hasegawa Tetsuya
  Appl. Phys. Express, 9, 2, 25801, 25801, 2016年
  英語, 研究論文（学術雑誌）
• Epitaxial growth and electronic structure of oxyhydride SrVO₂H thin films
  Katayama, T., Chikamatsu, A., Yamada, K., Shigematsu, K., Onozuka, T., Minohara, M., Kumigashira, H., Ikenaga, E., Hasegawa, T.
  Journal of Applied Physics, 120, 8, 2016年
  研究論文（学術雑誌）
• Effects of Cr substitution on the magnetic and transport properties and electronic states of SrRuO₃ epitaxial thin films
  Kaori Kurita, Akira Chikamatsu, Kei Shigematsu, Tsukasa Katayama, Hiroshi Kumigashira, Tomoteru Fukumura, Tetsuya Hasegawa
  PHYSICAL REVIEW B, 92, 11, 2015年09月29日
  英語, 研究論文（学術雑誌）
• Topotactic synthesis of strontium cobalt oxyhydride thin film with perovskite structure
  Katayama, T., Chikamatsu, A., Kamisaka, H., Yokoyama, Y., Hirata, Y., Wadati, H., Fukumura, T., Hasegawa, T.
  AIP Advances, 5, 10, 2015年
  研究論文（学術雑誌）
• Topotactic reductive fluorination of strontium cobalt oxide epitaxial thin films
  Katayama, T., Chikamatsu, A., Hirose, Y., Fukumura, T., Hasegawa, T.
  Journal of Sol-Gel Science and Technology, 73, 3, 2015年
  研究論文（学術雑誌）
• Effects of Cr substitution on the magnetic and transport properties and electronic states of SrRu O3 epitaxial thin films
  Kurita, K., Chikamatsu, A., Shigematsu, K., Katayama, T., Kumigashira, H., Fukumura, T., Hasegawa, T.
  Physical Review B - Condensed Matter and Materials Physics, 92, 11, 2015年
  研究論文（学術雑誌）
• Topotactic fluorination of strontium iron oxide thin films using polyvinylidene fluoride
  Katayama, T., Chikamatsu, A., Hirose, Y., Takagi, R., Kamisaka, H., Fukumura, T., Hasegawa, T.
  Journal of Materials Chemistry C, 2, 27, 2014年
  研究論文（学術雑誌）
• Metallic conductivity in infinite-layer strontium iron oxide thin films reduced by calcium hydride
  Katayama, T., Chikamatsu, A., Hirose, Y., Kumigashira, H., Fukumura, T., Hasegawa, T.
  Journal of Physics D: Applied Physics, 47, 13, 2014年
  研究論文（学術雑誌）
• Electronic and transport properties of Eu-substituted infinite-layer strontium ferrite thin films
  Chikamatsu, A., Matsuyama, T., Katayama, T., Hirose, Y., Kumigashira, H., Oshima, M., Fukumura, T., Hasegawa, T.
  Journal of Crystal Growth, 378, 2013年
  研究論文（学術雑誌）