2006 Fiscal Year Final Research Report Summary
Studies on control of spin ordering in magneto-dielectric thin films and their application for future electronics devices
| Project/Area Number |
17560621
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Osaka Prefecture University |
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Principal Investigator |
TOSHIYUKI Matsui Osaka Prefecture University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (20219372)
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| Co-Investigator(Kenkyū-buntansha) |
MORII Kenji Osaka Prefecture University, Graduate School of Engineering, Professor, 工学研究科, 教授 (10101198)
TSUDA Hiroshi Osaka Prefecture University, Graduate School of Engineering, Assistant Professor, 工学研究科, 講師 (80217322)
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| Project Period (FY) |
2005 – 2006
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| Keywords | magneto-dielectric thin film / magnetic properties / dielectric response / epitaxial growth / pulsed laser beam deposition / perovskite oxide / multiferroic / superexchange coupling |
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| Research Abstract |
The target of this research project is to synthesize room-temperature ferromagnetic dielectric thin films, which can possibly apply for novel magneto-dielectric devices. The followings are the main results obtained in the projects.
(1)The single crystalline BaFe_<1-x>Zr_x0_<3-δ> (x=0.0-0.8) thin films were successfully produced on (001) SrTiO_3 substrates by pulsed laser-beam deposition. The films were found to be highly resistive, up to the leakage current density of about 1.1x10^<-5> A/cm^2 at the bias electric field of 150 kV/cm for the x=0.7 sample. This is much less than 10^<-4> of that for the BaFe0_<3-δ>, single crystalline film, which implies that the dielectric properties have been distinctly improved by zirconium substitution. The magnetization loop measured at 5 K for the x=0.7 sample clearly shows hysteresis as well as the presence of the remanent magnetization. Hence, the magnetic ordering for the x=0.7 sample has been greatly enhanced, possibly due to the ferromagnetic spi
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n alignment of Fe ions. It should be worthwhile mentioning that the x=0.7 sample still exhibits a ferromagnetic characteristic at room temperature. Consequently, BaFe_<0.3>Zr_<0.7>0_<3-δ> is a potential candidate for practical use in some magnetoelectric devices, such as a ferroelectric-ferromagnetic gate field-effect-transistor in the near future.
(2)The single crystalline Ba(Co_<1-x>Mn_x)0_<3-δ> (x=0.2 and 0.7) films with the pseudo-cubic crystal structure were successfully synthesized. The films were found to be highly resistive with a dielectric constant of ε=5.2 at 5 K. In contrast, the films exhibited semiconductor-like conduction behavior at room temperature. Room temperature ferromagnetic ordering can be realized in samples with a saturation magnetization of 1.20 μB/fu for the x=0.2 sample, in contrast to 1.41 μB/fu for the x=0.7 sample. A possible origin of the observed magnetic ordering may be due to the superexchange coupling of Mn4+(d3)-O2--Co4+(d5) ions with a bonding angle of 180 degrees. Less
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Research Products
(11 results)
