| Project/Area Number |
07454063
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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 inScience and Engineering, Professor, 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 in Science and Engineering, As, 理工科学総合研究センター, 助手 (30260590)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1996: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1995: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | 3D TRANSITION METAL OXIDES / FEMTOSEOCND PUMP-PROBE SPECTROSCOPY / PHOTODOPING EFFECTS / FERROMAGNETIC-PARAMAGNETIC TRANSITION / CHARGE TRANSFER TRANSITION / 遷移金属酸化物 / 電荷移動遷移 / モット絶縁体 |
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| Research Abstract |
We have investigated change in electronic states by photodoping with femtosecond pulses and relaxation dynamics of photoexcited states in 3d transition metal oxides in order to elucidate interactions with phonons and magnons and relaxation processes characteristic of magnetic phases.
i) Relaxation dynamics of electronic states in CuO2 planes in cuprates. We have observed the photoinduced spectral change which is interpreted by the carrier doping effect by optical excitations. Optically induced in-gap states are relaxd in about 1 ps by emission of magnons, which indicates a crucial role of magnetic excitations in strongly correlated system.
ii) Preparation of 3d transition metal oxides films. Using a laser ablation technique we have fabricated many kind of oxides films.
Choosing an appropriate substrate temperature depending on materials we can fabricate transition metal oxides films such as cobaltates, nicklates and manganates.
iii) Optical spectra and relaxation dynamics associated with magnetic transitions. Temperature dependence of absorption spectra for thin films of double-exchange ferromagnet R0.6S_r0.4Mn03 has been investigated with variation of the one-electron band width. We have found that optical excitations in the visible region strongly couples with the local spin alignments in these doped manganates. Furthermore, we have investigated ultrafast spectral change induced by femtosecond pulse excitations. The femtosecond pulse doping induces change in local spin alignments and the paramagnetic domain is formed in 200 ps and this domain is converted into the ferromagnetic domain in about 100 ns. This is the first observation of dynamical behaviors of spins and local spin alignments in strongly correlated systems and demonstrates the controllability of the spin systems by means of irradiation of visible light. This may lead us to apply these materials to magneto-optical devices with a photon-mode.
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