2003 Fiscal Year Annual Research Report

レーザーMBE法で作製したペロブスカイトMn酸化物単結晶薄膜の角度分解光電子分光

Research Project

Project/Area Number	15740176
Research Institution	The University of Tokyo
Principal Investigator	組頭広志東京大学, 大学院・工学系研究科, 助手 (00345092)
Keywords	角度分解光電子分光 / レーザーMBE法 / 強相関遷移金属酸化物 / マンガン酸化物 / 巨大磁気抵抗効果 / 単結晶薄膜
Research Abstract	超巨大磁気抵抗効果に代表されるペロブスカイトMn酸化物が示す特異物性の発現機構を解明するために、Laser molecular-beam epitaxy(レーザーMBE)法を用いて、表面を原子レベルで制御しながらドープ量・バンド幅・次元性を系統的に変化させたペロブスカイトMn酸化物単結晶薄膜を製作し、その場(in situ)でARPES測定を行うことより、Mn酸化物薄膜のバンド構造を実験的に決定することに世界に先駆けて成功した。本実験を可能とするために、コンビナトリアルレーザーMBE法を駆使し、ペロブスカイトMn酸化物単結晶薄膜の成長条件の最適化を行った。これと並行して、建設・改良を進めてきた「レーザーMBE-光電子分光複合装置」のさらなる改良を行い、作製した薄膜の低温(〜15K)での高分解能(エネルギー分解能10meV、角度分可能0.25°)測定を可能にした。改良した装置を用いて、La_<1-x>Sr_xMnO_3(LSMO)のバンド構造の組成依存性を系統的に測定し、「点を中心としたエレクトロンポケットを明確に観測することに成功した。バンド計算との比較から、これはLSMOのハーフメタル的伝導に深く関わっていると考えられるMn 3de_g軌道に基づくmajority bandで形成されたエレクトロンボケットであると同定した。また、2.0eV近傍にフラットなMn 3dt_<2g>状態が存在し、2.3〜6eVには大きな分散を示すO 2p状態に基づくバンドが存在することを明らかにした。また、この電子面は、ホール濃度が増大するに伴ってその大きさが減少してゆき、強磁性相の消失と共に見えなくなるといったペロブスカイトMn酸化物の特異物性発現との相関関係を特定した。

Research Products

(14 results)

All Other

All Publications (14 results)

[Publications] H.Kumigashira et al.: "In-situ photoemission characterization of terminating-layer-controlled La_<0.6>Sr_<0.4>MnO_3 thin films"Applied Physics Letters. 82. 3430 (2003)
[Publications] K.Horiba et al.: "A high-resolution synchrotron-radiation angle-resolved photoemission system combined with a laser molecular beam epitaxy"Review of Scientific Instruments. 74. 3406 (2003)
[Publications] M.Oshima et al.: "Interfacial chemistry and structures of ultrathin Si oxynitride films"Applied Surface Science. 216. 291 (2003)
[Publications] K.Horiba et al.: "In-situ Mn 2p-3d resonant photoemission study on La_<0.6>Sr_<0.4>MnO_3 epitaxial thin films grown by laser MBE"Journal of Magnetism and Magnetic Materials. (In press). (2004)
[Publications] H.Kumigashira et al.: "In-situ synchrotron radiation angle-resolved photoemission study on La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular beam epitaxy"Journal of Magnetism and Magnetic Materials. (In press). (2004)
[Publications] H.Kumigashira et al.: "Surface electronic structures of terminating-layer-controlled La_<0.6>Sr_<0.4>MnO_3 thin films studied by in-situ synchrotron radiation photoemission spectroscopy"Journal of Magnetism and Magnetic Materials. (In press). (2004)
[Publications] M.Oshima et al.: "In-situ photoelectron spectroscopy of LaMnO_3 and La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular-beam expitaxy"Applied Physics Letters. 83. 2172 (2003)
[Publications] S.Toyota et al.: "Effect of nitrogen doping into SiO_2 studied by photoemission spectroscopy"Applied Physics Letters. 83. 5449 (2003)
[Publications] M.Oshima et al.: "Chemical states and band offsets of NH_3-treated Si oxynitride films studied by high-resolution photoelectron spectroscopy"Journal of Vacuum Science Technology. A22. 176 (2004)
[Publications] M.Oshima et al.: "In-situ photoelectron spectroscopy of LaMnO_3 and La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular-beam expitaxy"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)
[Publications] S.Toyoda et al.: "Effect interlayers and annealing on chemical states of HfO_2 gate insulators studied by photoemission spectroscopy"Applied Physics Letters. (In press). (2004)
[Publications] H.Kumigashira et al.: "In-situ photoemission spectroscopic study on La_<1-x>Sr_xMnO_3 thin films grown by combinatorial laser-MBE"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)
[Publications] S.Toyoda et al.: "Chemistry and band offsets of HfO_2 thin films revealed by photoelectronspectroscopy and x-ray absoroption spectroscopy"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)
[Publications] M.Nakayama et al.: "Ultrahigh-resolution angle-resolved photoemission spectroscopy of La- and Ce-monochalcogenides"Physical Review B. (In press). (2004)

2003 Fiscal Year Annual Research Report

レーザーMBE法で作製したペロブスカイトMn酸化物単結晶薄膜の角度分解光電子分光

Principal Investigator

組頭 広志 東京大学, 大学院・工学系研究科, 助手 (00345092)

Research Products

[Publications] H.Kumigashira et al.: "In-situ photoemission characterization of terminating-layer-controlled La_<0.6>Sr_<0.4>MnO_3 thin films"Applied Physics Letters. 82. 3430 (2003)

[Publications] K.Horiba et al.: "A high-resolution synchrotron-radiation angle-resolved photoemission system combined with a laser molecular beam epitaxy"Review of Scientific Instruments. 74. 3406 (2003)

[Publications] M.Oshima et al.: "Interfacial chemistry and structures of ultrathin Si oxynitride films"Applied Surface Science. 216. 291 (2003)

[Publications] K.Horiba et al.: "In-situ Mn 2p-3d resonant photoemission study on La_<0.6>Sr_<0.4>MnO_3 epitaxial thin films grown by laser MBE"Journal of Magnetism and Magnetic Materials. (In press). (2004)

[Publications] H.Kumigashira et al.: "In-situ synchrotron radiation angle-resolved photoemission study on La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular beam epitaxy"Journal of Magnetism and Magnetic Materials. (In press). (2004)

[Publications] H.Kumigashira et al.: "Surface electronic structures of terminating-layer-controlled La_<0.6>Sr_<0.4>MnO_3 thin films studied by in-situ synchrotron radiation photoemission spectroscopy"Journal of Magnetism and Magnetic Materials. (In press). (2004)

[Publications] M.Oshima et al.: "In-situ photoelectron spectroscopy of LaMnO_3 and La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular-beam expitaxy"Applied Physics Letters. 83. 2172 (2003)

[Publications] S.Toyota et al.: "Effect of nitrogen doping into SiO_2 studied by photoemission spectroscopy"Applied Physics Letters. 83. 5449 (2003)

[Publications] M.Oshima et al.: "Chemical states and band offsets of NH_3-treated Si oxynitride films studied by high-resolution photoelectron spectroscopy"Journal of Vacuum Science Technology. A22. 176 (2004)

[Publications] M.Oshima et al.: "In-situ photoelectron spectroscopy of LaMnO_3 and La_<0.6>Sr_<0.4>MnO_3 thin films grown by laser molecular-beam expitaxy"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)

[Publications] S.Toyoda et al.: "Effect interlayers and annealing on chemical states of HfO_2 gate insulators studied by photoemission spectroscopy"Applied Physics Letters. (In press). (2004)

[Publications] H.Kumigashira et al.: "In-situ photoemission spectroscopic study on La_<1-x>Sr_xMnO_3 thin films grown by combinatorial laser-MBE"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)

[Publications] S.Toyoda et al.: "Chemistry and band offsets of HfO_2 thin films revealed by photoelectronspectroscopy and x-ray absoroption spectroscopy"Journal of Electron Spectroscopy and Related Phenomena. (In press). (2004)

[Publications] M.Nakayama et al.: "Ultrahigh-resolution angle-resolved photoemission spectroscopy of La- and Ce-monochalcogenides"Physical Review B. (In press). (2004)

組頭広志東京大学, 大学院・工学系研究科, 助手 (00345092)