Field-effect doping of strongly correlated electron systems

• Project/Area Number: 17340105
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: The University of Tokyo
• Principal Investigator: LIPPMAA Mikk The University of Tokyo, Institute for Solid State Physics, Associate Professor, 物性研究所, 助教授 (10334343)
• Co-Investigator(Kenkyū-buntansha): OHNISHI Tsuyoshi The University of Tokyo, Institute for Solid State Physics, Research Associate, 物性研究所, 助手 (80345230)
• Project Period (FY): 2005 – 2006
• Project Status: Completed (Fiscal Year 2006)
• Budget Amount: ¥15,500,000 (Direct Cost: ¥15,500,000); Fiscal Year 2006: ¥8,500,000 (Direct Cost: ¥8,500,000); Fiscal Year 2005: ¥7,000,000 (Direct Cost: ¥7,000,000)
• Keywords: oxide / field effect / transistor / metal-insulator transition / SrTiO3 / mobility / superconductivity / nanowire / 強相関エレクトロニクス / マイクロ・ナノデバイス / MBE、エピタキシャル / 先端機能デバイス / 超薄膜

Research Abstract

During H18 we succeeded in fabricating SrTiO3-based field-effect transistors with epitaxial and amorphous CaHfO3 and DyScO3 gate insulator layers. Epitaxial insulator layers of CaHfO3 and DyScO3 could be grown on SrTiO3 to a thickness of about 2 nm without nucleating grain boundaries. By combining a thin epitaxial layer with an amorphous insulator, we achieved transistors where sheet carrier densities of 10^<13> cm^<-2> order could be induced in a thin surface layer of a SrTiO_3 substrate. A rapid increase of the field-effect mobility was observed at low temperature, indicating that the field-induced carriers are equivalent to chemically doped carriers. A metal-to-insulator transition was observed in the SrTiO_3 transistors.
The growth of metallic LaTiO_3 nanowires was studied. A step-flow growth technique was developed that allowed us to fabricate an array of metallic (La, Sr)TiO_3 nanowires along the step edges of an annealed SrTiO_3 substrate. A technique was developed to buffer the surface of an annealed SrTiO_3 single crystal surface with a SrO film pror to the growth of the LaTiO_3 nanowires. This step was necessary in order to reduce the surface conductivity of SrTiO_3 and thus isolate the nanowires from each other. The final nanowire arrays showed nearly ideal one-dimensional conductivity.
The superconducting properties of Nb-doped SrTiO_3 films were studied in collaboration with the group of prof. Triscone at the University of Geneva, Switzerland. We succeeded in fabricating superconducting Nb:SrTiO_3 thin films and demonstrated that the superconductivity can be switched on and off by changing the carrier concentration in the thin films by electrostatic field effect.

Research Products

• [Journal Article] Pulsed laser deposition of oxide thin films (2006)
  • Author(s): Ohnishi T, Koinuma H, Lippmaa M
  • Journal Title: APPLIED SURFACE SCIENCE 252・7 Pages: 2466-2466
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Local switching of two-dimensional superconductivity using the ferroelectric field effect (2006)
  • Author(s): Takahashi KS, Gabay M, Jaccard D, Shibuya K, Ohnishi T, Lippmaa M, Triscone JM
  • Journal Title: NATURE 441・7090 Pages: 195-195
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Robust Ti4+ states in SrTiO3 layers of LaO. 6Sr0.4MnO3 / SrTiO3 / LaO.6SrO.4MnO3 junctions (2006)
  • Author(s): Kumigashira H, Chikamatsu A, Hashimoto R, Oshima M, Ohnishi T, Lippmaa M, Wadati H, Fujimori A, Ono K, Kawasaki M, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 88・19 Pages: 192504-192504
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] In situ resonant photoemission characterization of LaO.6SrO.4MnO3 layers buried in insulating perovskite oxides (2006)
  • Author(s): Kumigashira H, Hashimoto R, Chikamatsu A, Oshima M, Ohnishi T, Lippmaa M, Wadati H, Fujimori A, Ono K, Kawasaki M, Koinuma H
  • Journal Title: JOURNAL OF APPLIED PHYSICS 99・8
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Ferromagnetism stabilization of ultrathin SrRuO3 films : Thickness-dependent physical properties (2006)
  • Author(s): Toyota D, Ohkubo I, Kumigashira H, Oshima M, Ohnishi T, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: JOURNAL OF APPLIED PHYSICS 99・8
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Field-effect modulation of the transport properties of nondoped SrTi03 (2006)
  • Author(s): Shibuya K, Ohnishi T, Uozumi T, Sato T, Lippmaa M, Kawasaki M, Nakajima K, Chikyow T, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 88・21 Pages: 212116-212116
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Temperature-dependent soft X-ray photoemission and absorption studies of charge disproportionation in La1-xSrxFeO3 (2006)
  • Author(s): Wadati H, Chikamatsu A, Hashimoto R, Takizawa M, Kumigashira H, Fujimori A, Lippmaa M, Kawasak M, Koinuma H
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75・5 Pages: 54704-54704
  • NAID: 210000106154
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Band structure and Fermi surface of LaO.6SrO.4MnO3 thin films studied by in situ angle-resolved photoemission spectroscopy (2006)
  • Author(s): Chikamatsu A, Wadati H, Kumigashira H, Oshima M, Fujimori A, Hamada N, Ohnishi T, Lippmaa M, Ono K, Kawasaki M, Koinuma H
  • Journal Title: PHYSICAL REVIEW B 73・19 Pages: 195105-195105
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices (2006)
  • Author(s): Takizawa M, Wadati H, Tanaka K, Hashimoto M, Yoshida T, Fujimori A, Chikamatsu A, Kumigashira H, Oshima M, Shibuya K, Mihara T, Ohnishi T, Lippmaa M, Kawasaki M, Koinuma H, Okamoto S, Millis AJ
  • Journal Title: PHYSICAL REVIEW LETTERS 97・5 Pages: 57601-57601
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Growth and characterization of epitaxial DyScO3 films on SrTiO3 (2006)
  • Author(s): Uozumi T, Shibuya K, Ohnishi T, Sato T, Lippmaa M
  • Journal Title: JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS ＆ EXPRESS LETTERS 45・29-32
  • NAID: 210000062021
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Observation of step-induced magnetic domain formation in La1-xSrxMnO3 thin films by photoelectron emission microscopy (2006)
  • Author(s): Taniuchi T, Kumigashira H, Oshima M, Wakita T, Yokoya T, Kubota M, Ono K, Akinaga H, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 89・11 Pages: 112505-112505
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Strong localization of doped holes in La1-xSrxFeO3 from angle-resolved photoemission spectra (2006)
  • Author(s): Wadati H, Chikamatsu A, Takizawa M, Hashimoto R, Kumigashira H, Yoshida T, Mizokawa T, Fujimori A, Oshima M, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: PHYSICAL REVIEW B 74・11 Pages: 115114-115114
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] An in situ transport measurement of interfaces between SrTiO3(100) surface and an amorphous wide-gap insulator (2006)
  • Author(s): Shibuya K, Ohnishi T, Uozumi T, Koinuma H, Lippmaa M
  • Journal Title: APPLIED SURFACE SCIENCE 252・23 Pages: 8147-8147
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Sulfur passivation of Ge (001) surfaces and its effects on Schottky barrier contact (2006)
  • Author(s): Maeda T, Takagi S, Ohnishi T, Lippmaa M
  • Journal Title: MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING 9・4-5 Pages: 706-706
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Combinatorial experimentation and materials informatics (2006)
  • Author(s): Takeuchi I, Lippmaa M, Matsumoto Y
  • Journal Title: MRS BULLETIN 31・12 Pages: 999-999
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] XML-based data management system for combinatorial solid-state materials science (2006)
  • Author(s): Meguro S, Lippmaa M, Ohnishi T, Chikyow T, Koinuma H
  • Journal Title: APPLIED SURFACE SCIENCE 252・7 Pages: 2634-2634
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Robust Ti4+ states in SrTiO3 layers of La0.6Sr0.4MnO3 / SrTiO3 / La0.6Sr0.4MnO3 junctions (2006)
  • Author(s): Kumigashira H, Chikamatsu A, Hashimoto R, Oshima M, Ohnishi T, Lippmaa M, Wadati H, Fujimori A, Ono K, Kawasaki M, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 88・19 Pages: 192504-192504
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] In situ resonant photoemission characterization of La0.6Sr0.4MnO3 layers buried in insulating perovskite oxides (2006)
  • Author(s): Kumigashira H, Hashimoto R, Chikamatsu A, Oshima M, Ohnishi T, Lippmaa M, Wadati H, Fujimori A, Ono K, Kawasaki M, Koinuma H
  • Journal Title: JOURNAL OF APPLIED PHYSICS 99・8
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Ferromagnetism stabilization of ultrathin SrRu03 films : Thickness-dependent physical properties (2006)
  • Author(s): Toyota D, Ohkubo I, Kumigashira H, Oshima M, Ohnishi T, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: JOURNAL OF APPLIED PHYSICS 99・8
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Field-effect modulation of the transport properties of nondoped SrTiO3 (2006)
  • Author(s): Shibuya K, Ohnishi T, Uozumi T, Sato T, Lippmaa M, Kawasaki M, Nakajima K, Chikyow T, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 88・21 Pages: 212116-212116
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Temperature-dependent soft X-ray photoemission and absorption studies of charge disproportionation in Lal-xSrxFeO3 (2006)
  • Author(s): Wadati H, Chikamatsu A, Hashimoto R, Takizawa M, Kumigashira H, Fujimori A, Lippmaa M, Kawasak M, Koinuma H
  • Journal Title: JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 75・5 Pages: 54704-54704
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Band structure and Fermi surface of La0.6Sr0.4MnO3 thin films studied by in situ angle-resolved photoemission spectroscopy (2006)
  • Author(s): Chikamatsu A, Wadati H, Kumigashira H, Oshima M, Fujimori A, Hamada N, Ohnishi T, Lippmaa M, Ono K, Kawasaki M, Koinuma H
  • Journal Title: PHYSICAL REVIEW B 73・19 Pages: 195105-195105
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Photoemission from buried interfaces in SrTiO3/LaTiO3 superlattices (2006)
  • Author(s): Takizawa M, Wadati H, Tanaka K, Hashimoto M, Yoshida T, Fujimori A, Chikamatsu A, Kumigashira H, Oshima M, Shibuya K, Mihara T, Ohnishi T, Lippmaa M, Kawasaki H, Koinuma H, Okamoto S, Millis AJ
  • Journal Title: PHYSICAL REVIEW LETTERS 97・5 Pages: 57601-57601
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Growth and characterization of epi taxial DyScO3 films on SrTiO3 (2006)
  • Author(s): Uozumi T, Shibuya K, Ohnishi T, Sato T, Lippmaa M
  • Journal Title: JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS ＆ EXPRESS LETTERS 45・29-32
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Observation of step-induced magnetic domain formation in Lal-xSrxMnO3 thin films by photoelectron emission microscopy (2006)
  • Author(s): Taniuchi T, Kumigashira H, Oshima M, Wakita T, Yokoya T, Kubota M, Ono K, Akinaga H, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 89・11 Pages: 112505-112505
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Strong localization of doped holes in Lal-xSrxFeO3 from angle-resolved photoemission spectra (2006)
  • Author(s): Wadati H, Chikamatsu A, Takizawa M, Hashimoto R, Kumigashira H, Yoshida T, Mizokawa T, Fujimori A, Oshima M, Lippmaa M, Kawasaki M, Koinuma H
  • Journal Title: PHYSICAL REVIEW B 74-11 Pages: 115114-115114
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Robust Ti4+ states in SrTiO3 layers of LaO.6SrO.4MnO3/SrTiO3/LaO.6SrO.4MnO3 junctions (2006)
  • Author(s): Kumigashira H, Chikamatsu A, Hashimoto R, Oshima M, Ohnishi T, Lippmaa M, Wadati H, Fujimori A, Ono K, Kawasaki M, Koinuma H
  • Journal Title: APPLIED PHYSICS LETTERS 88・19 Pages: 192504-192504
• [Journal Article] An in situ transport measurement of interfaces between SrtIo3(100)SURFACE AND AN AMORPHOUS WIDE-GAP INSULATOR (2006)
  • Author(s): Shibuya K, Ohnishi T, Uozumi T, Koinuma H, Lppmaa M
  • Journal Title: APPLIED SURFACE SCIENCE 252・23 Pages: 8147-8147
• [Journal Article] Pulsed laser deposition of oxide thin films (2006)
  • Author(s): T.Ohnishi, H.Koinuma, M.Lippmaa
  • Journal Title: Applied Surface Science Vol.252,issue 7 Pages: 2466-2471
• [Journal Article] Pulsed laser deposition and characterization of low-dimensional oxide structures (2006)
  • Author(s): M.Lippmaa
  • Journal Title: 応用物理 Vol.73,No.2 Pages: 303-308
  • NAID: 10020530922
• [Journal Article] An in situ transport measurement of interfaces between SrTiO_3(100) surface and an amorphous wide-gap insulator (2005)
  • Author(s): K.Shibuya, T.Ohnishi, T.Uozumi, H.Koinuma, M.Lippmaa
  • Journal Title: Applied Surface Science On-line 21 Nov.
• [Journal Article] Transport properties of ultrathin oxide films and nanostructures (2005)
  • Author(s): T.Mihara, K.Shibuya, T.Ohnishi, H.Koinuma, M.Lippmaa
  • Journal Title: Thin Solid Films Vol.486,Issue 1-2 Pages: 195-199
• [Journal Article] Sr surface segregation and water cleaning for atomically controlled SrTiO_3(001) substrates studied by photoemission spectroscopy (2005)
  • Author(s): D.Kobayashi, T.Ohnihsi, M.Lippmaa, et al.
  • Journal Title: Journal of Electron Spectroscopy and Related Phenomena Vol.144-147 Pages: 443-446
• [Journal Article] Spectral evidence for inherent "dead layer" formation at La_<1-x>Sr_yFeO_3/La_<1-x>Sr_xMnO_3 heterointerface (2005)
  • Author(s): R.Hashimoto, T.Ohnishi, M.Lippmaa, et al.
  • Journal Title: Journal of Electron Spectroscopy and Related Phenomena Vol.144-147 Pages: 479-481
• [Journal Article] In situ angle-resolved photoemission study on La_<1-x>Sr_xMnO_3 thin films grown by laser MBE (2005)
  • Author(s): A.Chikamatsu, T.Ohnishi, M.Lippmaa, et al.
  • Journal Title: Journal of Electron Spectroscopy and Related Phenomena Vol.144-147 Pages: 511-514
• [Journal Article] Hard X-ray photoemission study Mn 2p core-levels of La_<1-x>Sr_xMnO_3 thin films (2005)
  • Author(s): K.Horiba, M.Lippmaa, H.Koinuma, S.Shin, et al.
  • Journal Title: Journal of Electron Spectroscopy and Related Phenomena Vol.144-147 Pages: 557-559
• [Journal Article] In situ photoemission study of La_<1-x>Sr_xFeO_3 epitaxial thin films (2005)
  • Author(s): H.Wadati, M.Lippmaa, M.Kawasaki, H.Koinuma, et al.
  • Journal Title: Journal of Electron Spectroscopy and Related Phenomena Vol.144-147 Pages: 877-880
• [Journal Article] Flux-assisted reactive solid phase epitaxy of highly c-axis oriented Ru(Eu_<1.5>Ce_<0.5>) Sr_2Cu20_<10-δ> thin films (2005)
  • Author(s): W.Q.Lu, H.Koinuma, K.Shibuya, M.Lippmaa, et al.
  • Journal Title: Physica C : Superconductivity Vol.422,Issue 1-2 Pages: 46-50
• [Journal Article] Manifestation of correlation effects in the photoemission spectra of Ca_<1-x>Sr_xRuO_3 (2005)
  • Author(s): M.Takizawa, M.Lippmaa, M.Kawasaki, H.Koinuma, et al.
  • Journal Title: Physical Review B Vol.72 Pages: 60404-60404
• [Journal Article] In vacuo photoemission study of atomically controlled La_<1-x>Sr_xMnO_3 thin films : Composition dependence of the electronic structure (2005)
  • Author(s): K.Horiba, M.Lippmaa, K.Ono, M.Kawasaki, H.Koinuma, et al.
  • Journal Title: Physical Review B Vol.71 Pages: 155420-155420
• [Journal Article] Hole-doping-induced changes in the electronic structure of La_<1-x>Sr_xFeO_3: Soft x-ray photoemission and absorption study of epitaxial thin films (2005)
  • Author(s): H.Wadati, M.Lippmaa, M.Kawasaki, H.Koinuma, et al.
  • Journal Title: Physical Review B Vol.71 Pages: 35108-35108
• [Journal Article] Improved stoichiometry and misfit control in perovskite thin film formation at a critical fluence by pulsed laser deposition (2005)
  • Author(s): T.Ohnishi, M.Lippmaa, T.Yamamoto, S.Meguro, H.Koinuma
  • Journal Title: Applied Physics Letters Vol.87 Pages: 241919-241919
• [Journal Article] Thickness-dependent electronic structure of ultrathin SrRuO_3 films studied by in situ photoemission spectroscopy (2005)
  • Author(s): D.Toyota, T.Ohnishi, M.Lippmaa, H.Koinuma, et al.
  • Journal Title: Applied Physics Letters Vol.87 Pages: 162508-162508
• [Journal Article] Epitaxial growth and transport properties of Nb-doped SrTiO3 thin films (2005)
  • Author(s): K.S.Takahashi, T.Ohnishi, M.Lippmaa, J.-M.Triscone, et al.
  • Journal Title: Proceedings of SPIE Vol.5932