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1997 Fiscal Year Annual Research Report

スピン-電荷-光・結合系の相制御

Research Project

Project/Area Number 08CE2003
Research Category

Grant-in-Aid for COE Research

Research InstitutionThe University of Tokyo

Principal Investigator

宮野 健次郎  東京大学, 大学院・工学系研究科, 教授 (90167677)

Co-Investigator(Kenkyū-buntansha) 十倉 好紀  東京大学, 大学院・工学系研究科, 教授 (30143382)
内田 慎一  東京大学, 大学院・工学系研究科, 教授 (10114399)
内野倉 国光  東京大学, 大学院・工学系研究科, 教授 (20015564)
永長 直人  東京大学, 大学院・工学系研究科, 助教授 (60164406)
花村 栄一  東京大学, 大学院・工学系研究科, 教授 (70013472)
Keywordsスピン-電荷-光・結合系 / 光誘起相転移 / 強相関電子系 / モット絶縁体 / 量子スピン系 / 酸化物エレクトロニクス / 巨大磁気抵抗効果 / 場の理論
Research Abstract

本研究の目的は、いわゆる強相関電子系の学理を解明し、これを工学に応用するための基礎をつくることである。この系においては電子の持つスピン、電荷、軌道の自由度が、互いに強く相互作用しあうことによって極めて複雑な相転移を起こす。本研究では電場や磁場のような従来型の外場のみならず、特に光を用いた相制御を企図している。平成9年度はこの目標に沿って、研究を行い、以下のような成果を挙げた。
1.スピン-電荷結合系の光による相制御:(1)光によってキャリアを注入し相転移を誘起させることは本研究の中心課題である。Pr_<1-x>Ca_xMnO_3の電荷整列相を示す全ドープ領域において光誘起-絶縁体・金属(IM)転移を観測し、その励起スペクトル、金属相の熱安定性を測定した。これにより転移が電子的励起に基づくものであることを確認した。また、強磁性ドメインが生成すること(光強磁性効果)を磁化測定により確認した。(2)ペロブスカイト型マンガン酸化物の磁場によるIM転移時の電子構造変化を分光的に調べ、赤外-紫外光領域に及ぶ大きな光スペクトル変化(磁気クロミズム効果)および電荷ギャップの系統的変化を見いだした。また、同じく電荷整列相転移を示す、層状ニッケル酸化物での電荷・磁気・フォノン励起の温度依存性をラマン分光法を用いて調べ、電荷整列相での典型的特徴を明らかにした。(3)近赤外〜中赤外域におけるフェムト秒時間分解分光システムの立ち上げを行なった。Sr_2CuO_3のポンププローブ分光で、可視光励起に対し赤外域吸収の敏感な変化を見いだした。これは光励起によりスピン系の状態を大きく変化させうることを示すものである。
スピン-電荷結合系のスピニクス:(1)高温超伝導体の面間集団励起であるジョセフソン・プラズマモードのド-ピング及び磁場依存性を調べ、プラズマ周波数、減衰、そしてボルテックスのピン止めを制御するパラメータを決定した。また、スピンと電荷の空間分離によるストライプ秩序がド-ピング量1/8以上では、超伝導秩序と共存することを示した。(2)正孔ドープされた2本脚梯子系Sr_<14-x>Ca_xCu_<24>O_<41>の電気抵抗率、光学伝導度の異方性を測定し、高温超伝導体と同様にスピンギャップが電荷ダイナミックスの1次元性をもたらしていることを明らかにした。(3)CuGeO_3にMgを不純物として添加した単結晶で、スピンパイエルス秩序と反強磁性(AF)秩序の共存する相と一様なAF相の2種類が存在し、不純物濃度の関数として一次相転移をすることを発見した。この発見はCuGeO_3、および低次元AF磁性体の研究に新しい局面を開くものである。(4)柱状欠陥を導入したBi_2Sr_2Ca_2Cu_2O_<8+y>単結晶の磁束液体状態において、面間の位相コヒーレンスが増大する特徴的磁場が存在することを見出し、また、磁束系の相図を始めて静水圧下で測定し、相転移磁場が圧力と共に増大することを示した。(5)擬2次元有機伝導体(BEDT-TTF)_2XのAF絶縁相のスピン構造が格子と最も単純な整合関係にあることがわかり、モット絶縁体の典型例であることがわかった。
3.スピン-電荷-光・結合系の量子論と強相関エレクトロニクスの原理:(1)マンガン酸化物の相図を平均場近似の範囲内で軌道とスピンの両者の構造を最適化することで求め実験を良く再現することができた。さらに進んで強磁性相の軌道の揺らぎを動的平均場理論で扱い、同位体効果やラマン散乱の結果を解析した。(2)1次元の半導体量子細線や2次元量子ホール液体のエッジなどの朝永-ラッティンジャー流体における量子輸送現象に関し、スピン一重項の効果,外部リ-ド線によるメソスコピック効果などを理論的に明らかにした。(3)相関の強い系に対する電子構造計算のために、GW法の新しい方法を定式化しプログラムを作成した。(4)LDA+U法をMn系ペロブスカイトNd_<1-x>Sr_xMnO_3に適用し、X=0.5近傍の電子構造を調べ、磁気、軌道秩序状態が実験結果と良く一致した。(5)強相関電子系であるAF酸化クロムの非線形光学応答の理論的解明を行い、倍高調波発生の微視的機構の全てを理解した。

  • Research Products

    (99 results)

All Other

All Publications (99 results)

  • [Publications] K.Miyano: "Photonduced Insulator-to-Metal Transition in a Perovskite Manganite" Phys.Rev.Lett.78(22). 4257-4260 (1997)

  • [Publications] T.Mori: "Spatial Properties of the Photoinduced Transition in Pr_<0.7>Ca_<0.3>MnO_3" J.Phys.Soc.Jpn. 66. 3570-3576 (1997)

  • [Publications] T.Shibauchi: "Josephson plasma resonance in the mixed state of organic superconductor κ-(BEDT-TTF)2Cu(NCS)2" Phys.Rev.B55. R11977 (1997)

  • [Publications] T.Shibauchi: "Observation of the plasma resonance across the Josephson-coupled layers in the mixed state of organic superconductors" Physica. C293. 73 (1997)

  • [Publications] T.Tamegai: "Phase coherence along the c-axis in Bi_2Sr_2CaCu_2O_8 with columnar defects probed by Josephson plasma resonance" Physica. C293. 224 (1997)

  • [Publications] T.Shibauchi: "Josephson plasma resonance in Bi_2Sr_2CaCu_2O_8 with columnar defects" Physica. C282-287. 2472 (1997)

  • [Publications] S.Ooi: "Vortex lattice melting and the peak effect in oblique field in Bi_2Sr_2CaCu_2O_8" Physica. C282-287. 1965 (1997)

  • [Publications] T.Tamegai: "Effects of hydrostatic pressure and oxygen doping on the vortex phase diagram in Bi_2Sr_2CaCu_2O_8" Physica. C282-287. 2029 (1997)

  • [Publications] D.T.Fuchs: "Sublimation and hysteretic transition of the Vortex lattice in Bi_2Sr_2CaCu_2O_8" Physica. C282-287. 2023 (1997)

  • [Publications] T.Shibauchi: "Strong Reduction of Quasiparticle Scattering Rate with Gap Formation in CeNiSn" Phys.Rev.B56. 8277-8281 (1997)

  • [Publications] T.Shibauchi: "Vortex phase transition with decoupling of adjacent layers in the organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br" Phys.Rev.B57. R5622 (1998)

  • [Publications] M.Sato: "Recoupling of decoupled vortex liquid by columnar defects in Bi_2Sr_2CaCu_2O_<8+y>" Phys.Rev.Lett.79. 3759 (1997)

  • [Publications] R.Yamada: "Pressure effect on the vortex phase diagram in Bi_2Sr_2CaCu_2O_<8+y>" Rev.High Pres.Sci.Technol.(to be published).

  • [Publications] D.T.Fuchs: "Transport properties governed by surface barriers in Bi_2Sr_2CaCu_2O_8" Nature. 391. 373 (1999)

  • [Publications] A.Oral: "Disorder-driven'Intermediate'State in the Lattice Melting Transition of Bi_2Sr_2CaCu_2O_<8+y> Single Crystals" Phys.Rev.B56. R14295 (1997)

  • [Publications] A.Oral: "Direct observation of Melting of the Vortex Solid in Bi_2Sr_2CaCu_2O_<8+y> Single Crystals" Phys.Rev.Lett.(to be published).

  • [Publications] H.Kuroe: "Spin fluctuations in CuGeO_3 probed by light scattering" Phys.Rev.B55. 409-415 (1997)

  • [Publications] Y.Sasago: "Temperature dependent spin gap and singlet ground state in BaCuSi_2O_6" Phys.Rev.B55. 8357-8360 (1997)

  • [Publications] A.Zheludev: "Field-induced commensurate-incommensurate phase transition in a Dzyaloshinkii-Moriya spiral antiferromagnet" Phys.Rev.Lett.78. 4857-4860 (1997)

  • [Publications] M.C.Martin: "Spin-Peierls and antiferromagnetic phases in Cu_<1-x>Zn_xGeO_3 : A neutron scattering study" Phys.Rev.B56. 3173-3180 (1997)

  • [Publications] K.M.Kojima: "Antiferromagnetic order with spatially inhomogeneous ordered moment size of Zn- and Si-doped CuGeO_3" Phys.Rev.Lett.79. 503-506 (1997)

  • [Publications] A.Zheludev: "Spiral order in Ba_2CuGe_2O_7" Physica. B234-236. 546-548 (1997)

  • [Publications] T.Shibauchi: "Strong reduction of quasiparticle scattering rate with gap formation in CeNiSn" Phys.Rev.B56. 8277-8281 (1997)

  • [Publications] I.Terasaki: "Large thermoelectric power in NaCo_2O_4 single crystals" Phys.Rev.B56. R12685-12687 (1997)

  • [Publications] A.Zheludev: "The square-lattice spiral magnet Ba_2CuGe_2O_7 in an in-plane magnetic field" Phys.Rev.B56. 14006-14012 (1997)

  • [Publications] 内野倉國光: "二次元スパイラル反強磁性体Ba_2CuGe_2O_7" 日本物理学会誌. 52. 847-850 (1997)

  • [Publications] A.Zheludev: "Field-induced incommensurate-to-commensurate transition in Ba_2CuGe_2O_7" Phys.Rev.B57. 2968-2978 (1998)

  • [Publications] S.Kobayashi: "Multiple LMTO Method and Down-Folding" Phys.Rev.B55(12). 7445-53 (1997)

  • [Publications] T.Fujiwara: "Optimized Ultrasoft Pseudopotentials" J.Phys.Soc.Jpn.66(6). 1723-29 (1997)

  • [Publications] T.Hoshi: "Fully-selfconsistent electronic-structure calculation using non-orthogonal localized orbitals within finite-difference real-space scheme and ultra-soft pseudopotential" J.Phys.Soc.Jpn.66(12). 3710-13 (1997)

  • [Publications] R.Shimano: "Nonlinear optical responses of exciton-microcavity coupled system in weak and intermediate coupling regime" J.Luminescence. 72-74. 297-299 (1997)

  • [Publications] D.J.Norris: "Excitation of a single molecule on the surface of a spherical microcavity" Appl.Phys.Lett.71. 297-299 (1997)

  • [Publications] Makoto Kuwata-Gonokami: "Prametric Scattering of Cavity Polaritons" Phys.Rev.Lett.79. 1341-1344 (1997)

  • [Publications] G.Mohs: "FAILURE OF THE MODAL GAIN MODEL IN A GaN BASED LASER DIODE" Solid State Commun.104. 643-648 (1997)

  • [Publications] Masaya Nagai: "Spherical cavity-mode laser with self-organized CuCl microspheres" OPTICS LETT.22. 1630-1632 (1997)

  • [Publications] Makoto Kuwata-Gonokami: "Polymer whispering gallery mode lasers" Optical Materials accepted for publication.

  • [Publications] Ryo Shimano: "Nonlinear optical processes of excitons in semiconductor microcavity structures" MATERIALS SCIENCE & ENGINEERING B. B48. 59-65 (1997)

  • [Publications] Takao Aoki: "Polarization dependent quantum beats of homogeneously broadened excitons" OPTICS EXPRESS. 1. 364-369 (1997)

  • [Publications] Keiji Horiuchi: "Photoluminescence Characterization of High-Purity Synthesized Diamond" JJAP. 36. 1505-1507 (1997)

  • [Publications] Y.Kawabe: "Whispering-gallery-mode mirroring laser using a conjugated polymer" Appl.Phys.Lett.72. 141-143 (1998)

  • [Publications] Y.Tanabe: "Theory of Nonlinear Optical Susceptibilities of Antiferromagnetic Cr_2O_3" Solid State Commun.102(9). 643-646 (1997)

  • [Publications] E.Hanamura: "Raman vs Rayleigh scattering due to core exciton" Phys.Rev.B56(11). 6384 (1997)

  • [Publications] H.Ezaki: "Photon number squeezing enhanced by two-photon process in excitonic systems" Optics Commun.138. 65-70 (1997)

  • [Publications] E.Hanamura: "Photo-Induced Structure Changes of Quasi-one-dimensional Organic Crystals" Springer-Series in Solid-State Sciences. 124. 34-44 (1997)

  • [Publications] E.Hanamura: "Microscopic model of magneto-electric spectroscopy in antiferromagnetic Cr_2O_3" J.Luminescence,. in print.

  • [Publications] T.Iizuka-Sakano: "Linear and Non-Linear Optical Responses of a Strongly Coupled Electron-Lattice System" J.Phys.Soc.Japan. 67(1). 332-339 (1998)

  • [Publications] M.Muto: "Magneto-electric and second harmonic spectra in antiferromagnetic Cr_2O_3" Phys.Rev.(B)in print.

  • [Publications] Y.Nakazawa: "Low-Temperature Specific Heat of k-(BEDT-TTF)2Cu[N(CN)2]Br in the Superconducting State" Phys.Rev.B55. R8670-R8673 (1997)

  • [Publications] A.Kawamoto: "Deuterated k-(BEDT-TTF)2Cu[N(CN)2]Br : a System on the Border of the Superconductor/Magnetic-Insulator Transition" Phys.Rev.B55. 14140-14143 (1997)

  • [Publications] Y.Nakazawa: "Reply to the ″Comment on 'Electronic structure of insulating salts of the k-(BEDT-TTF)2X family studied by low-temperature specific heat measurements" Phys.Rev.B56. 951-952 (1997)

  • [Publications] K.Kanoda: "Electron Correlation,Metal-Insulator Transition and Superconductivity in Quasi-2D Organic Systems,(ET)2X" Physica. C282-287. 299-302 (1997)

  • [Publications] K.Kanoda: "13C and 1H NMR Study of Vortex Dynamics in Layered Organic Superconductor at Selective Nuclear Sites" Physica. C282-287. 2063-2064 (1997)

  • [Publications] Y.Nakazawa: "Thermodynamic Property of Organic Superconductor k-(BEDT-TTF)2X[X=Cu(NCS)2,Cu[N(CN)2]Br]" Physica. C282-287. 1897-1898 (1997)

  • [Publications] H.Taniguchi: "Melting and Interlayer Coherence of Vortices in the Quasi-Two-Dimensional Organic Superconductor,a-(BEDT-TTF)2NH4Hg(SCN)4" Physica. C282-287. 2013-2014 (1997)

  • [Publications] I.Shirotani: "Superconductivity of Filled Skutterudites LaRu4As12 and PrRu4As12" Phys.Rev.B56. 7866-7869 (1997)

  • [Publications] K.Miyagawa: "13C-NMR Nesting Instability in a-(BEDT-TTF)2RbHg(SCN)4" Phys.Rev.B56. R8487-R8490 (1997)

  • [Publications] H.Taniguchi: "Phase Diagram of Vortices in the Quasi-Two-Dimensional Organic Superconductor,a-(BEDT-TTF)2NH4Hg(SCN)4 ; a System of Pancake Vortices with Out-of-Plane coupling dominated by the Electromagnetic Energy" Phys.Rev.in press. B57. (1998)

  • [Publications] S.Ishihara: "Orbital Liquid in La_<1-x>Sr_xMnO_3" Phys.Rev.B56(2). 686-692 (1997)

  • [Publications] K.Imura: "Quantum Transport in Two-Channel Fractional Hall Edges" Phys.Rev.B55(12). 7690-7701 (1997)

  • [Publications] P.Lee: "An SU(2) Formulation of the t-J model : Application to Underdoped Cuprates" to appear in Phys.Rev.(cond-mat/9701168). B.

  • [Publications] V.Ponomarenko: "Threshold Features in Transport through a 1D Constriction" Phys.Rev.Lett.79(9). 1714-1717 (1997)

  • [Publications] N.Nagaosa: "Kondo Effect in High-Tc Cuprates" Phys.Rev.Lett.79. 3755-3758 (1997)

  • [Publications] N.Nagaosa: "Effects of Impurities in Spin Gap State of Cuprates" Physica. C282-287. 283-287 (1997)

  • [Publications] H.Suzuura: "Spin-Charge Separation in Angle Resolved Photoemission Spectra" Phys.Rev.B56(7). 3548 (1997)

  • [Publications] N.Nagaosa: "Quantum Aspects of (Anti-)Ferroelectrics" Biuletyn Instytute Chemii Fizycznej i Teoretyczne. 5. 113-119 (1997)

  • [Publications] K.Imura: "Effects of long-range Coulomb interction on the quantum transtort in fractional quantum Hall edges" to appear in Solid State Commun.

  • [Publications] V.Ponomarenko: "From Tomonaga-Luttinger to Fermi liquid in transport through a tunneling barrier" Phys.Rev.B56(20). R12756-12759 (1997)

  • [Publications] S.Ishihara: "Optical Spectra in Charge Ordered Perovskite" J.Phys.Soc.Jpn.66(11). 3678-3682 (1997)

  • [Publications] S.Ishihara: "Orbital fluctuation in perovskite manganites" Physica. B237-238. 54-55 (1997)

  • [Publications] M.Yamanaka: "Conductance through a magnetic domain wall in double exchange system" Physica. B237-238. 28-29 (1997)

  • [Publications] K.Imura: "Quantum transport in Fractional Quantum Hall Effect" Physica. B(to appear).

  • [Publications] N.Nagaosa: "Electron-electron interaction and Jahn-Teller interaction in manganese oxides" Phys.Rev.B57(12)(to appear). (1998)

  • [Publications] K.Imura: "Quantum Transport in ν=2/3spin-singlet quantum Hall edges" Phys.Rev.B57(12)(to appear). (1998)

  • [Publications] S.Murakami: "Yangian symmetry and quantum inverse scattering method for the one-dimensional Hubbard model" Phys.Lett.A227. 216-226 (1997)

  • [Publications] Frank Goehmann: "Algebraic and analytic properties of the one-dimensional Hubbard model" J.Phys.A:Math.Gen.30. 5269-5287 (1997)

  • [Publications] Shuichi Murakami: "Algebraic Solution of the Hubbard Model on the Infinite Interval" Nucl.Phys.B512. 637-680 (1998)

  • [Publications] Tomoko Tsujikawa: "Metalorganic Vapor Phase Epitaxy Growth Features of AlGaAs in Tetrahedral-Shaped Recesses on GaAs(111)B Substrates" Jpn.J.Appl.Phys.36(6B). 4102-4106 (1997)

  • [Publications] Baoping Zhang: "Naturally formed ZnCdSe quantum dots on ZnSe(110) surfaces" Appl.Phys.Lett.70(18). 2413-2415 (1997)

  • [Publications] Jun Wu: "Crystal Structure of GaN Grown on 3C-SiC Substrates by Metalorganic vapor Phase Epitaxy" Jpn.J.Appl.Phys.36(7A). 4241-4245 (1997)

  • [Publications] Jun Wu: "Photoluminescence properties of cubic GaN grown on GaAs(100) substrates by metalorganic vapor phase epitaxy" Appl.Phys.Lett.71(15). 2067-2069 (1997)

  • [Publications] Baoping Zhang: "Self Formation and Optical Properties of II-VI Semiconductor Wire Structures" Jpn.J.Appl.Phys.36(11B). L1490-L1493 (1997)

  • [Publications] Seiro Miyoshi: "Growth Mechanism in the Metalorganic Vapor Phase Eptiaxy of Metastable GaP1-xNx Alloys : A Growth Interruption Study" Jpn.J.Appl.Phys.36(12A). 7110-7118 (1997)

  • [Publications] Baoping Zhang: "Self Formation and Photoluminescence of II-VI Quantum Wires on GaAs(110) Surfaces" Nonlinear Optics. 18(2-4). 133-136 (1997)

  • [Publications] Tomoko Tsujikawa: "GaAs/AlGaAs Low-dimensional Structures Grown in Tetrahedral-Shaped Recesses on GaAs(111)B Substrates by Metalorganic Vapor Phase Epitaxy" Physica. B(to be published).

  • [Publications] Jun Wu: "Metalorganic Vapor Phase Epitaxy Growth of High Quality Cubic GaN on GaAs(100) Substrates" Jpn.J.Appl.Phys.37(3)(to be published). (1998)

  • [Publications] Tomoko Tsujikawa: "GaAs/AlGaAs Quantum Structures Grown in Tetrahedral-Shaped Recesses on GaAs(111)B Substrates by MOVPE" Jpn.J.Appl.Phys.(to be published).

  • [Publications] Mitsuteru Ishikawa: "Polarization Characteristics of Crescent-Shaped Tensile-Strained GaAsP/AlGaAs Quantum Wire-Like Lasers" Jpn.J.Appl.Phys.(to be published).

  • [Publications] Hiroyuki Yaguchi: "Temperature Dependence of Photoluminescence of GaP_<1-x>N_x Alloys" J.Crystal Growth. (to be published).

  • [Publications] Goshi Biwa: "Metalorganic Vapor Phase Epitaxy of GaP_<1-x-y>As_yN_x Quaternary Alloys on GaP" J.Crystal Growth. (to be published).

  • [Publications] Jun Wu: "Optical Transition in Cubic GaN Grown on GaAs(100) Substrates by Metalorganic Vapor Phase Epitaxy" J.Crystal Growth. (to be published).

  • [Publications] Jun Wu: "Investigation of Luminescence Properties of GaN Single Crystals Grown on 3C-SiC Substrates" J.Crystal Growth. (to be published).

  • [Publications] Fujio Shimizu: "Holographic manipulatrion of an atomic beam" Mat.Science and Engineering. B48. 7-12 (1997)

  • [Publications] H.Kunugida: "Ionizing collisional rate of Metastable rare gas atoms in an optical lattice" Phys.Rev.Let.79. 621-624 (1997)

  • [Publications] Y.Murakami: "Direct observation of charge-and orbital-ordering in La_<0.5>Sr_<1.5>MnO_4" Phys.Rev.Lett.(in press). (1998)

  • [Publications] T.Ishikawa: "Optical probe of anisotropic and incoherent charge dynamics in a layered ferromagnet : La_<1.2>Sr_<1.8>Mn_2O_7" Phys.Rev.57(in press). (1998)

  • [Publications] Y.Okimoto: "Photonic phase control of magnetic oxides" J.Liq.Cryst.Mol.Cryst.(in press). (1998)

  • [Publications] Y.Okimoto: "Charge ordering and disordering transitions in Pr_<1-x>Ca_xMnO_3" Phys.Rev.B57(in press).

  • [Publications] A.Chainani: "Temperature dependence of the electronic structure of the charge-ordering manganite Pr_<0.5>Sr_<0.5>MnO_3" Phys.Rev.B56. R15513-R15516 (1997)

  • [Publications] T.Kimura: "Pressure-enhanced interplane tunneling magnetoresistance in a layered manganite crystal" Phys.Rev.Lett.79. 3720-3723 (1997)

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Published: 1999-03-15   Modified: 2014-04-22  

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