2002 Fiscal Year Final Research Report Summary
Dynamics of Self-Induced Quantum Vortices in Ferromagnetic Superconductor RuSr2YCU2O8
| Project/Area Number |
13440112
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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 |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | Osaka University |
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Principal Investigator |
KITAOKA Yoshio Osaka University, Graduate School of Engineering Science, Professor, 基礎工学研究科, 教授 (70110707)
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| Co-Investigator(Kenkyū-buntansha) |
AKIMITSU Jun Aoyama-Gakuin University, Department of Physics, Professor, 理工学部, 教授 (80013522)
ISHIDA Kenji Osaka University, Graduate School of Engineering Science, Assistant Professor, 基礎工学研究科, 助手 (90243196)
ZHENG Guo-qing Osaka University, Graduate School of Engineering Science, Associate Professor, 基礎工学研究科, 助教授 (50231444)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Layered Magnetic High-Temperature Duprate-Oxide Superconductor / Coexistence of Ferrmagnetism and Superconductivity / NMR / RuSr_2YCu_2O_8 / Eu_<2-x>Ce_xRuSr_2Cu_2O_<10-d> / Multilayered High-Temperature Cuprate-Oxide Superconductor / Coexistence of Antiferrmagnetism and Superconductivity / HgBa_2Ca_4Cu_5O_<10+y> |
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| Research Abstract |
Frora Ru- and Cu MKR studies, we have presented evidence for coexistence of superconductivity and ferroraagnetism in a cuprate superconductor RuSr_2YCu_2O_H (RuY1212). The observation of a large enhancement of a radio-frequency field for the Ru-NMR signal at zero field reveals the existence of a ferromagnetic (FM) component in the ordered RuO_2 plane below a Curie temperature of T_M = 150 K. Just best below the onset temperature of superconductivity Tc(onset)= 45 K, a remarkable decrease of the nuclear spin-lattice relaxation rate 1/T_I was observed within the ordered RuO_2 plane as well as the CuO_2 plane revealing that the superconducting gap coexists with the FM component in the RuO_2 plane on a microscopic scale. In addition, from the the observation of a sharp pesk in ^<10>(L/T_I) at Tc(zero) 〜23 K where the resistivity becomes zero, we suggest that the motion of self-induced vortices originating from fluctuations of the FM component induces the resistivity between T c(onset) and T c(zero) in RuY1212.
We alos have reported a coexistence of superconductivity and antiferromagnetism in five-layered compound HgBa_2Ca_4Cu_5O_y (Hg-1245) with T_c=108 K, which is composed of two types of CuO_2 planes in a unit cell, Three inner planes (IP) and twe outer planes (OP). The Cu-NMR study study has revealed that the optimally-doped OP undergoes a supercondcting (SC) transition at T_c=108 K, whereas the three underdoped IP's do an antiferromagnetic (AF) transition below T_x〜60 K with the Cu moments of 〜0.3-0.4μ_<K^+> The AF spin polarization at the IP is found to induce an internal fied at the SC OP. The observed metallic behavior at the IP gives the possibility that SC and AF order parameter coexist in a single CuO_2 plane.
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