“放射光を利用した物性科学の発展と展望” 研究会 原研放射光科学研究センター、2004年3月18-19日 f 電子系超伝導体の軟X線放射光分光 藤森 淳 （東大新領域、原研放射光） 共同研究者 藤森伸一、斎藤祐児、岡根哲夫、岡本淳、中谷健、村松康司（原研放射 光） 間宮一敏（KEK－PF） 島田賢也、成村孝正、小林賢一、生天目博文、谷口雅樹（広島大放射光） 池田修悟、青木 大、宍戸寛明（阪大理） 芳賀芳範、山本悦嗣、松田達麿（原研先端研） 大貫惇睦（阪大理、原研先端研） 山上浩志、常盤欣文（京都産業大）、播磨尚朝（阪大産研） 田中 新（広島大先端物質） Outline • JAERI beamline BL-23SU – PES – MCD • Ce and U exotic superconductors – Ce115 compounds: superconductivity near QCP • U115 compounds – Ferromagnetic superconductor UGe2 – Antiferromagnetic superconductor UPd2Al3 Beamlines in Spring-8 RI samples (U compounds) JAERI beamline BL-23SU of Spring-8 monochromator front end (Hettrick-Underwood type) fast closing gate valve beam shutter absorber variablypolarizing undulator beam-transport pipe RI inspection port 1 -stopper XYslit fixed mask entrance slit u =12cm Np=16 Mv beam position monitor M3 VLSPG experimental hall 20 10 30 APPLE-2 u=12cm N=16 S1 40 50 175° M1 M2 179° 174° 176° M3 Mh 40000 75000 42500 S2 10000 ST1 ST2 M4 60955 80 73910 114000 100 110 120 130 140 176° G1 61338 500 1000 1500 2000 photon energy (eV) top view cylindrical mirror 90 176° G2 200 177° Hot Sample Area 174° G2 10955 50000 70 radiation detector ST3 71910 955 60 M4 cryopump system Distance to source point (m) G1: 1000 lines/mm G2: 600 lines/mm 61910 Mv 2500 0 177° fluorescence screen RI inspection port 3 biological application station VLSPG side view fluorescence screen beam monitor surface photochemistry station hutch for optics 0 acitinide science station XY slit exit slit M 1,M2 Mh fluorescence screen fast closing gate valve RI inspection port 2 fast closing gate valve spherical mirror 177° entrance slit cylindrical mirror grating spherical mirror exit slit toroidal mirror cylindrical mirror 177° Y. Saitoh et al., Nucl. Instrum. Methods A ’01. JAERI beamline BL-23SU of Spring-8 Y. Saitoh et al., Rev. Sci. Instrum. ’ 00 JAERI beamline BL-23SU of Spring-8 monochromator front end (Hettrick-Underwood type) fast closing gate valve absorber variablypolarizing undulator fixed mask beam shutter entrance slit Mv beam position monitor M3 VLSPG experimental hall 10 20 30 fluorescence screen beam monitor biological application station 40 50 60 70 80 SynchrotronDistance to source point (m) Radiation PES station Scienta 2002, Gammadata VUV5000 MCD station Superconducting magnet, up to 10 T Low temperature, down to 10 K U compounds can be measured fluorescence screen surface photochemistry station hutch for optics MCD装置 0 acitinide science station XY slit exit slit M 1,M2 Mh fluorescence screen fast closing gate valve RI inspection port 2 fast closing gate valve -stopper XYslit u =12cm Np=16 ARPES装 置 beam-transport pipe RI inspection port 1 PES M4 cryopump system radiation detector RI inspection port 3 Hot Sample Area 90 100 110 MCD 120 130 140 Resonant photoemission S.I. Fujimori et al Resonant photoemission A. Sekiyama et al., Nature ‘00. K. Shimada et al. Angle-resolved photoemission (ARPES) MCD in core-level x-ray absorption from metal 2p core level spin sum rule Apple II-type helical undulator orbital sum rule Element-selective magnetic probe Superconducting magnet, up to 10 T Low temperature, down to 10 K A1 - A2 Outline • JAERI beamline BL-23SU – PES – MCD • Ce and U exotic superconductors – Ce115 compounds: superconductivity near QCP • U115 compounds – Ferromagnetic superconductor UGe2 – Antiferromagnetic superconductor UPd2Al3 Superconductivity near quantum critical point Doniach’s phase diagram Non-Fermi liquid Antferromagnetic metal superconducting Fermi liquid quantum critical point S. Doniach G.G. Lonzarich Quasi-2D superconductors near quantum critical point CeTIn5 (T=Rh, Ir, Co) In antiferromagnetic Rh, Ir Ce Superconductivity at ambient pressure in CeIrIn5 (TC = 0.4 K) and CeCoIn5 (TC = 2.2 K) supercond. H. Hegger et al. PRL ‘00 H. Shishido et al. PRB ‘02 Quasi-2D superconductors near quantum critical point CeTIn5 (T=Rh, Ir, Co) Doniach’s phase diagram H. Shishido et al. JPSJ 02 CeCoIn5 Non-Fermi liquid CeRhIn5 CeIrIn5 superconducting Antferromagnetic metal Fermi liquid quantum critical point pressure S. Doniach G.G. Lonzarich Resonant photoemission and XAS Ce 3d-4f Ce 4d-4f @ Hi-SOR Ce 3d XAS @ Spring-8 S.I. Fujimori et al., PRB ‘03 S.I. Fujimori et al., Physica C ‘03 nf ~ 1 spin-orbit sideband CeRhIn5: AREPS and band-structure calculations hn = 21.2 eV S.I. Fujimori et al., PRB ‘03 Band calc: H. Harima CeIrIn5: AREPS and band-structure calculations hn = 21.2 eV S.I. Fujimori et al., PRB ‘03 Band calc: H. Harima ARPES Fermi surfaces in CeIrIn5 Fermi surface mapping compared with LDA Fermi surface of CeIrIn5 by LDA calculation H. Harima A M S.I. Fujimori et al., PRB ‘03 Hybridized spd-f band model Ce compound Wf La compound f band spd band Hybridized spd-Ce 4f bands in CeIrIn5 He I (hn = 21.2 eV) → sp 4d-4f RPES (hn = 122 eV) → Ce 4f @ Hi-SOR S.I. Fujimori et al. Outline • JAERI beamline BL-23SU – PES – MCD • Ce and U exotic superconductors – Ce115 compounds: superconductivity near QCP • U115 compounds – Ferromagnetic superconductor UGe2 – Antiferromagnetic superconductor UPd2Al3 Quasi-2D UTGa5 (T = Fe, Pt) UTGa5 UGa3 U Fe, Pt Ga Ga Fe, Pt U UFeGa5 : paramagent UPtGa5 : antiferromagnet (TＮ=26K) cf) PuCoGa5: superconductor (TC=18.5K) Photoemission spectra of UTGa5 (T = Fe, Pt) U 5f PM sensitivity AFM U 5f Fe 3d U 5f S.I. Fujimori et al. Band structure and Fermi surfaces of UFeGa5 wide 5f band Fermi surface mapping S.I. Fujimori et al. Band calc: H. Yamagami Photoemission spectra of UTGa5 (T = Fe, Pt) U 5f PM sensitivity AFM U 5f Fe 3d U 5f S.I. Fujimori et al. Band structure of UPtGa5 narrow 5f band S.I. Fujimori et al. Outline • JAERI beamline BL-23SU – PES – MCD • Ce and U exotic superconductors – Ce115 compounds: superconductivity near QCP • U115 compounds – Ferromagnetic superconductor UGe2 – Antiferromagnetic superconductor UPd2Al3 Ferromagentic superconductor UGe2 ferromagnetic T* new order parameter ? supercond. TCurie = 52 K TSC = 0.8 [email protected] GPa T* ~ 30 K: anomaly ? S. S. Saxena et al., Nature ‘00 A. Huxley et al., PRB ‘01 N. Tateiwa et al., JPSJ ‘01 TCurie T* U M4,5 (3d 5f) MCD of U compounds US Raw data (TFY method) self-absorption effects Corrected data matrix-element effects ?? S.P. Collins et al., J. Phys. Cond. Mat. ‘95 U N4,5 (4d 5f) MCD of UGe2 mL mS mL/mS 2.9 -1.5 -1.9 U4+ 2.37 -0.91 -2.60 U3+ 2.62 -1.17 -2.24 2.98 -1.52 -1.46 MCD (T=25K) Neutron diffraction LDA T. Okane et al. Neutron: Keranvanois et al., PRB ‘01 U N3 (4p 6d), Ge L2,3 (2p 4s) MCD of UGe2 No polarization of U 6d electrons Finite Ge L2,3 MCD Finite polarization of Ge 4s electrons T. Okane et al. U N4,5 (4d 5f) MCD of UGe2 mL mS mL/mS 2.9 -1.5 -1.9 U4+ 2.37 -0.91 -2.60 U3+ 2.62 -1.17 -2.24 2.98 -1.52 -1.46 MCD (T=25K) Neutron diffraction LDA T. Okane et al. Neutron: Keranvanois et al., PRB ‘01 U N4,5 MCD of UGe2 : Temperature dependence T* TCurie T. Okane et al. Outline • JAERI beamline BL-23SU – PES – MCD • Ce and U exotic superconductors – Ce115 compounds: superconductivity near QCP • U115 compounds – Ferromagnetic superconductor UGe2 – Antiferromagnetic superconductor UPd2Al3 Antiferromagentic superconductors UPd2Al3 UNi2Al3 UPt3 a = 5.382 Å c = 4.189 Å a = 5.027 Å c = 4.018 Å a = 5.764 Å c = 4.899 Å TN= 14K(0.85mB) TC= 2 K TN= 2.4K(0.24mB) TC= 1 K TN= 5 K(0.02mB) TC= 0.4 K U 5f electrons localized itinerant Photoemission spectra of UPd2Al3 S.I. Fujimori et al. Conclusions • Ce115 compounds: superconductivity near QCP – Ce 4f electrons are nearly localized, nf ~ 1. – but participates in band/Fermi surface formation in CeIrIn5. • U115 compounds – Different degrees of localization have been demonstrated between UFeGa5 and UPtGa5. • Ferromagnetic superconductor UGe2 – Spin and orbital moments and their temperature dependence have been obtained by MCD – with no anomaly at ~T* • High (optimized) beamline performance has been achieved at BL-23SU. – Many scientific opportunities are foreseen. Scientific opportunities at BL-23SU • U compounds – SX-AREPS, MCD, core-level XPS • Basic sciences of strong correlation – 3-dimensional transition-metal oxides -- SX-ARPES – Ferromagnetic oxides -- MCD • Nano-sciences – Diluted magnetic semiconductors -- MCD at low-T, high-H – Oxide thin films, interfaces, nano-structures – Intercalation, nano-magnets, ….. Combined in situ PES-PLD system PES PLD CCD Cameras SR cf. Oshima group at KEK-PF Scientific opportunities at BL-23SU • U compounds – SX-AREPS, MCD, core-level XPS • Basic sciences of strong correlation – 3-dimensional transition-metal oxides -- SX-ARPES – Ferromagnetic oxides -- MCD • Nano-sciences – Diluted magnetic semiconductors -- MCD at low-T, high-H – Oxide thin films, interfaces, nano-structures – Intercalation, nano-magnets, ….. • New directions: Proposals are welcome ! 原研放射光・電子物性研究グループ ■研究テーマ "強相関電子系機能性材料の電子構造に関する研究" 超伝導や巨大磁気抵抗など特異な物性を示す遷移金属、希土類、ウランを含む強相関電子 系物質とこれらの物質を複合化、ナノ構造化した新しい機能を持つ物質・材料の化学結合状 態・電子構造を各種軟x線分光法を用いて明らかにする。得られた情報から物質設計・材料設 計の指針を得てIT、環境、エネルギーに関連した新材料の開発に資する。 ■メンバー 安居院あかね / Akane Agui 岡根哲夫 / Tetsuo Okane 岡本淳 / Jun Okamoto 博士研究員 斉藤祐児 / Yuji Saitoh 竹田幸治 / Yukiharu Takeda 博士研究員 竹山雅義 / Masayoshi Takeyama 業務協力員 寺井恒太 / Kota Terai 博士研究員 中谷健 / Takeshi Nakatani 藤森淳 / Atsushi Fujimori 客員研究員 藤森伸一 / Shinichi Fujimori 村松康司 / Yasuji Muramatsu グループリーダー
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