| Project/Area Number |
10440091
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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Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Nagoya University |
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Principal Investigator |
NAKAMURA Arao Nagoya University, Center for Integrated Research of Science and Engineering, Prof., 理工科学総合研究センター, 教授 (50159068)
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| Co-Investigator(Kenkyū-buntansha) |
ICHIDA Masao Nagoya University, Center for Integrated Research of Science and Engineering, Assistant Prof., 理工科学総合研究センター, 助手 (30260590)
MORITOMO Yutaka Nagoya University, Center for Integrated Research of Science and Engineering, Associated Prof., 理工科学総合研究センター, 助教授 (00283466)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2000: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1999: ¥5,500,000 (Direct Cost: ¥5,500,000)
Fiscal Year 1998: ¥8,100,000 (Direct Cost: ¥8,100,000)
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| Keywords | perovskite manganites / photoinduced phase transition / double exchange system / ferromagnetic phase transition / ultrafasst laser spectroscopy / half-metal / 超高速レーザー分光 / ペルプスカイト型酸化物 / 電荷移動遷移 / ヤーンテラーポーラロン / ペルブスカイト型酸化物 / スモールポーラロン |
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| Research Abstract |
We have systematically investigated electric, magnetic and optical properties of structure- and valencecontrolled manganites which show photoinduced magnetic transitions. The following is a major result.
1. The temperature variations of the resistivity and specific heat have been measured for prototypical half-metallic ferromagnets R_<0.6>Sr_<0.4>MnO_3 by controlling the one-electron band width. We have observed the T^3 dependence of the resistivity which is interpreted in terms of the anomalous single-magnon scattering process in the half-metallic system.
2. Photoinduced spin disorder and its dynamical behavior have been investigated for La_<0.7>Ca_<0.3>MnO_3. By optical injection of down-spin electrons into the Mn e_g orbital the spin disorder in the ferromagnetic phase is induced. We have found that the recovery time to the spin ordered state is lengthened from 30 ns at 5 K to 30 μs when the temperature approaches to the critical temperature of the phase transition. This result clearly demonstrates the critical slowing down of relaxation time in the phase transition.
3. Photoinduced resistivity change in a La_<0.6>Ca_<0.4>MnO_3 film has been investigated with variation of the excitation photon energy and temperature. The magnitude of the photoinduced resistivity change steeply decreases with increasing temperature above the transition temperature of 315 K.Since the photoinduced signal is enhanced by injection of the down spin carriers, the resistivity change is ascribed to the photoinduced spin disorder in the ferromagnetic metallic state. This result indicates that one can detect photoinduced spin disorder with the resistivity signal.
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