| Project/Area Number |
15340109
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HIROTA Kazuma The University of Tokyo, Institute for Solid State Physics, Associate Professor, 物性研究所, 助教授 (90272012)
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| Co-Investigator(Kenkyū-buntansha) |
ASO Naofumi The University of Tokyo, Institute for Solid State Physics, Research Associate, 物性研究所, 助手 (40313118)
KIMURA Hiroyuki Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Research Associate, 多元物質科学研究所, 助手 (50312658)
MATSUURA Masato The University of Tokyo, Institute for Solid State Physics, Research Associate, 物性研究所, 助手 (30376652)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥14,900,000 (Direct Cost: ¥14,900,000)
Fiscal Year 2005: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥4,800,000 (Direct Cost: ¥4,800,000)
Fiscal Year 2003: ¥7,000,000 (Direct Cost: ¥7,000,000)
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| Keywords | high T_c superconductivity / La_<2-x>Sr_xCuO_4 / Neutron scattering / One-dimensional spin modulation / Spin dynamics / Bi high T_c superconductors / Impurity effect / Bi_2Sr_<2-x>La_xCuO_6 / Bi_2Sr_2CaCu_2O_8 / Dewtinning / La_<2-x>Sr_XCuO_4 |
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| Research Abstract |
Since it is difficult to grow large single crystals for highly anisotropic or domain-controlled high T_c superconductors, it is necessary to increase the effective volume by aligning multiple crystals to carry out neutron scattering. We thus have established a method to align many single crystals precisely and efficiently : Combination of a high-energy x-ray diffractometer and a CCD camera, as well as a supersensitive CCD camera with neutron scintillator have been developed. We have succeeded in obtaining the effective volume of 0.53cc by aligning six Bi2212 single crystals with a very high precision, which is about eight times as large as a typical sample volume in previous studies. We have been carrying out series of neutron scattering experiments at the Oak Ridge National Laboratory through the US-Japan cooperative program on neutron scattering to search for the magnetic excitation and the resonance peak.
To elucidate the relation between superconductivity and antiferromagnetic spin dynamics, we have performed a systematic inelastic neutron scattering concerning the suppression of T_c by impurities and the change of the spin excitations, using optimally doped La_<2-x>Sr_xCuO_4 single crystals with very small amount of impurities. We have focused upon the non-magnetic impurity Zn and the magnetic impurity Ni : Since the former suppresses T_c more effectively the latter, we expected to clarify how the magnetism is related to the T_c suppression mechanism by comparing both the systems. As to the Zn doped system, a novel in-gap state appears in the middle of the previously know spin gap while the overall spin dynamics does not change much. On the other hand, the spin dynamics of the Ni doped systems is renormalized to the lower energies as T_c is suppressed. It is now clear that the Zn and Ni doping effects on the superconductivity on the CuO_2 plane is qualitatively different.
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