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31 results on '"Ogimoto, Yasushi"'

1. Polar Antiferromagnets Produced with Orbital-Order

Author

Ogawa, Naoki, Ogimoto, Yasushi, Ida, Yoshiaki, Nomura, Yusuke, Arita, Ryotaro, and Miyano, Kenjiro

Subjects
Condensed Matter - Strongly Correlated Electrons
Abstract

Polar magnetic states are realized in pseudocubic manganite thin films fabricated on high-index substrates, in which a Jahn-Teller (JT) distortion remains an active variable. Several types of orbital-orders were found to develop large optical second harmonic generation, signaling broken-inversion-symmetry distinct from their bulk forms and films on (100) substrates. The observed symmetry-lifting and first-principles calculation both indicate that the modified JT q2 mode drives Mn-site off-centering upon orbital order, leading to the possible cooperation of "Mn-site polarization" and magnetism., Comment: 5 pages, 4 figures

Published
2011
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2. Enhanced dielectric response by disordered nanoscale/mesoscopic insulators

Author

Onoda, Shigeki, Chern, Chyh-Hong, Murakami, Shuichi, Ogimoto, Yasushi, and Nagaosa, Naoto

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Materials Science
Abstract

Enhancement of the dielectric response of insulators by disorder is theoretically proposed, where the quantum interference of electronic waves through the nanoscale/mesoscopic system and its change due to external perturbations control the polarization. In the disordered case with all the states being localized, the resonant tunneling, which is topologically protected, plays a crucial role, and enhances the dielectric response by a factor 30~40 compared with the pure case. Realization of this idea with accessible materials/structures is also discussed., Comment: 4 pages including 3 figures; minor revision; a high-resolution figure available at http://appi.t.u-tokyo.ac.jp/~sonoda/papers.html

Published
2006
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5. Near-field assisted magnetic recording

Author

Miyanishi, Shintaro, Iketani, Naoyasu, Takayama, Kazuhisa, Innami, Kohsuke, Suzuki, Ippei, Kitazawa, Tazuko, Ogimoto, Yasushi, Murakami, Yoshiteru, Kojima, Kunio, and Takahashi, Akira

Subjects
Magnetic recorders and recording -- Research, Magnetic fields -- Observations, Hard disks -- Magnetic properties, Hard disk drive, Under 5GB hard disk drive, 5GB - 9.99GB hard disk drive, 10GB - 14.99GB hard disk drive, 15GB - 19.99GB hard disk drive, 20GB - 25GB hard disk drive, Over 25GB hard disk drive, Business, Electronics, Electronics and electrical industries
Abstract

We propose a new hybrid head that generates both the magnetic field and the near field on a nano-sized region for high-density magnetic recording. Utilizing this hybrid head, the narrowest track width of 70 nm is achieved on TbFeCo media, which proves the near-field assisted magnetic recording beyond the diffraction limit of an optical pickup. The hybrid head demonstrated here constitutes a breakthrough toward the areal density of 1 Tb/[in.sup.2]. Index Terms--Hybrid head, near-field assisted magnetic recording, surface plasmon, TbFeCo.

Published
2005

7. Detection of spins and charge states in centrosymmetric materials by nonlinear optics

Author

Satoh, Takuya, Lottermoser, Thomas, Fiebig, Manfred, Ogimoto, Yasushi, Tamaru, Hiroharu, Izumi, Makoto, and Miyano, Kenjiro

Subjects
Dielectric films -- Research, Thin films -- Research, Magnetic fields -- Research, Physics
Abstract

Nonlinear optics is applied to two types of centrosymmetric magnetic materials and shown to be a powerful complement to linear optics. The interfaces of centrosymmetric thin films on manganite heterostructure by interface-sensitive second harmonic generation are investigated.

Published
2005

12. Transient photoinduced ‘hidden’ phase in a manganite

Author

Ichikawa, Hirohiko, primary, Nozawa, Shunsuke, additional, Sato, Tokushi, additional, Tomita, Ayana, additional, Ichiyanagi, Kouhei, additional, Chollet, Matthieu, additional, Guerin, Laurent, additional, Dean, Nicky, additional, Cavalleri, Andrea, additional, Adachi, Shin-ichi, additional, Arima, Taka-hisa, additional, Sawa, Hiroshi, additional, Ogimoto, Yasushi, additional, Nakamura, Masao, additional, Tamaki, Ryo, additional, Miyano, Kenjiro, additional, and Koshihara, Shin-ya, additional

Published
2011
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29. Phase control through anisotropic strain in Nd0.5Sr0.5MnO3 thin films.

Author

Nakamura, Masao, Ogimoto, Yasushi, Tamaru, Hiroharu, Izumi, Makoto, and Miyano, Kenjiro

Subjects
*THIN films, *STRAINS & stresses (Mechanics), *ANISOTROPY, *PHASE transitions, *CRYSTALLOGRAPHY, *PROPERTIES of matter
Abstract

Strain effect in charge- and orbital-ordered state has been investigated for Nd0.5Sr0.5MnO3 thin films deposited on (100), (110), and (111)-oriented substrates of SrTiO3. Films on (001) and (111) substrates have a monotonous temperature dependence for magnetic and transport properties showing no first-order phase transition. On the other hand, films on (110) substrate show a clear ferromagnetic-antiferromagnetic and metal-insulator transition around 170 K similar to that in a bulk single crystal, which is a manifestation of the charge and orbital order. Precise control of the hole concentration was also demonstrated around half doping. [ABSTRACT FROM AUTHOR]

Published
2005
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30. Pseudomorphic strain effect on the charge-orbital ordering pattern in Pr0.5Sr0.5MnO3 epitaxial thin films.

Author

Ogimoto, Yasushi, Takubo, Naoko, Nakamura, Masao, Tamaru, Hiroharu, Izumi, Makoto, and Miyano, Kenjiro

Subjects
*THIN films, *SOLID state electronics, *THICK films, *MAGNETIC fields, *SOLIDS, *SURFACES (Technology), *SURFACE coatings
Abstract

We accomplished coherent epitaxial growth of a Pr0.5Sr0.5MnO3 thin film on (LaAlO3)0.3–(SrAl0.5Ta0.5O3)0.7 (110) substrate, which demonstrates a robust charge-orbital ordering (COO) phase transition. In addition to the isotropic transport properties, a drastic recovery of high-resistivity state (>20 Ω cm) from a field-cooled metallic state (∼0.5 mΩ cm) was observed at 5 K with a release of a magnetic field. These results indicate a possible modification of COO pattern into CE-type COO state [d(3x2-r2/3y2-r2)] in the film from A-type stripe COO state [d(x2-y2)] observed in bulk samples by a substrate-induced strain. [ABSTRACT FROM AUTHOR]

Published
2005
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31. Stability of spontaneous polarization in ultrathin improper ferroelectrics.

Author

Zhigao Sheng, Ogawa, Naoki, Ogimoto, Yasushi, and Miyano, Kenjiro

Subjects
*POLARIZATION (Electricity), *FERROELECTRIC thin films, *ZIRCONIUM oxide, *THIN films, *ELECTROSTATICS
Abstract

The competition between the substrate-induced strain and the electrostatic polarization in improper ferroelectric films (hexagonal YMnO3) has been studied using optical second-harmonic generation techniques. Deposited on a (111) surface of yttria-stabilized zirconia substrate, the films exhibit (1) strong strain with negligible polarization, (2) relaxation accompanied by the nonlinear buildup of the polarization, and (3) bulklike polar behavior, in the order of increasing film thickness. The role of the substrate is distinctively different from that in proper ferroelectrics. [ABSTRACT FROM AUTHOR]

Published
2011
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