2010S2-001
軟X線偏光スイッチングを用いたスピントロニクス材料の探求

Last modified 2018-01-25 by s-proposalpfiqst.kek.jp

●基本情報
　●実験責任者：雨宮　健太（PF）
　●課題有効期間：2010/4〜2013/3
　●実験ステーション：16A, 7A
　●関連課題：2013S2-004（外的要因による磁性薄膜の特性制御を目指した 軟X線XMCDを中心とする相補的研究）

●課題の概要
　現在PF-BL-16Aでは，軟X線領域(250-1500 eV)において10 Hz程度の高速偏光スイッチング(左右円偏光および水平・垂直直線偏光)の開発を進めている。この技術を軟X線吸収および軟Ｘ線共鳴散乱における磁気円二色性(XMCD)・線二色性(XMLD)に適用すれば，ロックイン法を用いることによって，直流測定では10^-2程度が検出下限であったXMCD, XMLDにおいて10^-4-10^-5の極微小シグナル検出が可能になる。本研究では，このような極微小シグナル検出技術を確立し，それを利用して，以下に示すようなスピントロニクス材料の探究を行う。
(1) 強相関電子系における多様な物性，様々な相の競合の解明，および超格子秩序における電荷・スピン・軌道整列の同定。さらに，相転移近傍でのそれらの臨界的挙動の解明。界面・ナノ構造における新奇現象の探索と解明。
(2) 室温で強磁性を示す希薄磁性半導体における，微量の磁性不純物元素の磁気モーメントと母体非磁性元素の誘起磁気モーメントの元素選択的な決定，および異なるサイトにおける磁気成分の分離。これらをもとにした，より実用的な材料の探索。
(3) 磁性薄膜・多層膜における異種金属・酸化物の界面1～数原子層(特に比較的深い所に埋もれた界面)の磁性および化学状態の決定。これをいかした高性能材料の設計。

●成果発表
　●論文

• "Phase diagram of Ca_1-xCe_xMnO₃ thin films studied by X-ray magnetic circular dichroism"
  T. Harano, G. Shibata, K. Yoshimatsu, K. Ishigami, V.K. Verma, Y. Takahashi, T. Kadono, T. Yoshida, A. Fujimori, T. Koide, F.-H. Chang, H.-J. Lin, D.-J. Huang, C.-T. Chen, P.-H. Xiang, H. Yamada, A. Sawa
  Solid State Comm., 207 (2015) 50.
• "Magnetic Field Dependence of the Canted Spin Moment around the Interface between Ferromagnetic Ni and Antiferromagnetic FeMn Revealed by the Polarized Neutron Reflectivity"
  Kenta Amemiya, Masako Sakamaki, Mari Mizusawa, and Masayasu Takeda
  JPS Conf. Proc., 8 (2015) 034004.
• "Electronic and magnetic properties of off-stoichiometric Co₂Mn_βSi/MgO interfaces studied by x-ray magnetic circular dichroism"
  V.R. Singh, V.K. Verma, K. Ishigami, G. Shibata, A. Fujimori, T. Koide, Y. Miura, M. Shirai, T. Ishikawa, G.-f. Li, M. Yamamoto
  J. Appl. Phys., 117 (2015) 203901.
• "Thickness-dependent ferromagnetic metal to paramagnetic insulator transition in La_0.6Sr_0.4MnO₃ thin films studied by x-ray magnetic circular dichroism"
  G. Shibata, K. Yoshimatsu, E. Sakai, V.R. Singh, V.K. Verma, K. Ishigami, T. Harano, T. Kadono, Y. Takeda, T. Okane, Y. Saitoh, H. Yamagami, A. Sawa, H. Kumigashira, M. Oshima, T. Koide, and A. Fujimori
  Phys. Rev. B, 89 (2014) 235123.
• "Enhancement of perpendicular magnetic anisotropy by compressive strain in alternately layered FeNi thin films"
  Masako Sakamaki and Kenta Amemiya
  J. Phys.: Condens. Matter, 26 (2014) 166002.
• "Twisted magnetic structure in ferromagnetic ultrathin Ni films induced by magnetic anisotropy interaction with antiferromagnetic FeMn"
  Kenta Amemiya, Masako Sakamaki, Mari Mizusawa, and Masayasu Takeda
  Phys. Rev. B, 89 (2014) 054404.
• "Phase diagram of Ca_1-xCe_xMnO₃ thin films studied by X-ray magnetic circular dichroism"
  T. Harano, G. Shibata, K. Yoshimatsu, K. Ishigami, V.K. Verma, Y. Takahashi, T. Kadono, T. Yoshida, A. Fujimori, T. Koide, F.-H. Chang, H.-J. Lin, D.-J. Huang, C.-T. Chen, P.-H. Xiang, H. Yamada, A. Sawa
  Solid State Comm., 174 (2013) 30.
• "Spectroscopic studies on the electronic and magnetic states of Co-doped perovskite manganite Pr_0.8Ca_0.2Mn_1-yCo_yO₃ thin films"
  K.Yoshimatsu, H.Wadati, E.Sakai, T. Harada, Y.Takahashi, T.Harano, G.Shibata, K.Ishigami, T.Kadono, T.Koide, T.Sugiyama, E.Ikenaga, H.Kumigashira, M.Lippmaa, M.Oshima, and A.Fujimori
  Phys. Rev. B, 88 (2013) 174423.
• "Ar⁺ ion milling-induced suppression of surface oxidation in Fe₇₀Co₃₀ thin films"
  Masako Sakamaki, Kenta Amemiya, Akira Nambu, Kazuhiro Ueda, Jun-ichiro Shimizu, Katsuro Watanabe
  Materials Chemistry and Physics, 143 (2013) 281.
• "Temperature Dependence of Remanent Magnetization of Thin Films at the Interface to a Nonmagnetic Material: Cu/Ni/Cu(100)"
  K.Amemiya and M.Sakamaki
  Phys. Rev. B, 88 (2013) 014401.
• "Fast Polarization Switching in the Soft X-Ray Region at PF BL-16A"
  K.Amemiya, M.Sakamaki, T.Koide, K.Ito, K.Tsuchiya, K.Harada, T.Aoto, T.Shioya, T.Obina, S.Yamamoto and Y.Kobayashi
  J. Phys. Conf. Ser., 425 (2013) 152015.
• "Operation of a Fast Polarization-Switching Source at the Photon Factory"
  K.Tsuchiya, T.Shioya, T.Aoto, K.Harada, T.Obina, M.Sakamaki and K.Amemiya
  J. Phys. Conf. Ser., 425 (2013) 132017.
• "Ga⁺ Ion Irradiation-Induced Changes in Magnetic Anisotropy of a Pt/Co/Pt Thin Film Studied by X-Ray Magnetic Circular Dichroism"
  K.Amemiya, M.Sakamaki, P.Mazalski, I.Sveklo, Z.Kurant, A.Maziewski, M.O.Liedke, J.Fassbender, A.Wawro and L.T.Baczewski
  EPJ Web of Conferences, 40 (2013) 08002.
• "Effect of Structural Strain on Magnetic Anisotropy Energy of Each Element in Alternately Layered FeNi Thin Films"
  M.Sakamaki and K.Amemiya
  Phys. Rev. B, 87 (2013) 014428.
• "X-Ray Absorption Spectroscopy and X-Ray Magnetic Circular Dichroism Studies of Transition-Metal-Codoped ZnO Nano-Particles"
  T.Kataoka, Y.Yamazaki, V.R.Singh, Y.Sakamoto, K.Ishigami, V.K.Verma, A.Fujimori, F.-H.Chang, H.-J.Lin, D.J.Huang, C.T.Chen, D.Asakura, T.Koide, A.Tanaka, D.Karmakar, S.K.Mandal, T.K.Nath and I.Dagupta
  e-J. Surf. Sci. Nanotech., 10 (2012) 594.
• "Effects of Off-Stoichiometry on the Spin Polarization at the Co₂Mn_βGe_0.38/MgO Interfaces: X-Ray magnetic Circular Dichroism Study"
  V.R.Singh, V.K.Verma, K.Ishigami, G.Shibata, T.Kadono, A.Fujimori, D.Asakura, T.Koide, Y.Miura, M.Shirai, G.-f.Li, T.Taira and M.Yamamoto
  Phys. Rev. B, 86 (2012) 144412.
• "Perpendicular Magnetic Anisotropy in a Pt/Co/Pt Ultrathin Film Arising from a Lattice Distortion Induced by Ion Irradiation"
  M.Sakamaki, K.Amemiya, M.O.Liedke, J.Fassbender, P.Mazalski, I.Sveklo and A.Maziewski
  Phys. Rev. B, 86 (2012) 024418.
• "XAFS and XMCD Spectra at the Surface and Interface of Ultrathin Films Observed by the Depth-Resolved XAFS/XMCD Technique"
  K.Amemiya and M.Sakamaki
  e-J. Surf. Sci. Nanotech., 10 (2012) 521.
• "Sub-nm Resolution Depth Profiling of the Chemical State and Magnetic Structure of Thin Films by a Depth-Resolved X-Ray Absorption Spectroscopy Technique"
  K.Amemiya
  Phys. Chem. Chem. Phys., 14 (2012) 10477.
• "Observation of Magnetic Moments at the Interface Region in Magnetic Tunnel Junctions using Depth-resolved X-Ray Magnetic Circular Dichroism"
  S.Tsunegi, Y.Sakuraba, K.Amemiya, M.Sakamaki, E.Ozawa, A.Sakuma, K.Takanashi and Y.Ando
  Phys. Rev. B, 85 (2012) 180408(R).
• "In Situ Observation of Magnetic Anisotropy Energy of Alternately Layered FeNi Thin Films"
  M.Sakamaki and K.Amemiya
  e-J. Surf. Sci. Nanotech., 10 (2012) 97.
• "Element Specific Magnetic Anisotropy Energy of Alternately Layered FeNi Thin Films"
  M.Sakamaki and K.Amemiya
  Appl. Phys. Exp., 4 (2011) 073002.
• "NiO-Like Single Layer Formed on a Ni/Cu(001) Thin Film Revealed by the Depth-Resolved X-Ray Absorption Spectroscopy"
  K.Amemiya and M.Sakamaki
  Appl. Phys. Lett., 98 (2011) 012501.