論文 - 小堀 裕己
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Magneto-Transport Properties and Hole Self-Doping due to Excess Oxygen Addition in Polycrystalline LaMnO3 査読あり
H. Kobori,M. Sogabe, A. Hoshino, T. Taniguchi and T. Shimizu
Materials Science Forum 1053 55 - 60 2022年2月
担当区分:筆頭著者
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Evidence of Hole Self-Doping due to Excess Oxygen Addition in Polycrystal LaMnO3 査読あり
Hiromi Kobori, Megumi Sogabe, A. Hoshino, A. Yamasaki, T. Taniguchi and T. Shimizu
Materials Science Forum 1023 9 - 13 2021年3月
単著
担当区分:筆頭著者 出版者・発行元:Trans Tech Publications Ltd, Switzerland
We have presented the evidence of hole self-doping due to excess oxygen addition in
polycrystal LaMnO3 (LMO). The polycrystal LMO samples were prepared by use of a solid-state
reaction method. Powder mixtures with a molar ratio of 1:1 between La2O3 and Mn2O3 were
pre-annealed at 1100ºC for 18 hours in the atmospheres of oxygen gas, helium gas and vacuum. By
this heat treatment, non-crystalline LMO samples were produced. After that, the non-crystalline
LMO samples were grinded and were pressed into pellets at the pressure of 3t/cm3. The pellets were
annealed at 1100ºC and 1300ºC for 18 hours in the same atmospheres as the pre-annealing. Through
these processes, polycrystal LMO samples were finally produced. To investigate crystallographic
structure of the LMO samples, X-ray diffraction (XRD) measurements were performed by use of
Cu-K radiation. From the experimental results of XRD measurements, we have found that all LMO
samples have perovskite structure and are polycrystals. In addition, to investigate surface structure of
the LMO samples, scanning electron microscope (SEM) measurements were carried out. Electrical
resistivities (ERs) of the polycrystal LMO samples were measured as a function of temperature
(4K-300K). The ERs of polycrystal LMO samples produced in an oxygen gas atmosphere show lower
values as compared with other LMO ones in He gas and vacuum atmospheres. Especially, the
temperature dependence of the ER for a polycrystal LMO sample produced at the annealing
temperature of 1100ºC in an oxygen atmosphere shows a metallic behavior. Thus, we have
considered that this LMO sample has the largest hole self-doping concentration in all LMO ones. -
Magneto-Transport Properties in LaMnO3 Thin Films on a-SiO2 Substrates Produced by Metal Organic Decomposition Method 査読あり
H. Kobori,a, T. Kitamura, A. Yamasaki, T. Taniguchi and T. Shimizu
Key Engineering Materials 853 63 - 67 2020年
共著
担当区分:筆頭著者
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Strong Hole Self-Doping in LaMnO3 Thin Film on a-SiO2 Substrate produced by Metal Organic Decomposition Method 査読あり
H. Kobori, T. Kitamura, T. Taniguchi and T. Shimizu
Materials Science Forum 2019年
共著
担当区分:筆頭著者
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Enhanced Magnetoresistance in Fe3O4/Si Thin Films Prepared by Rapid Thermal Deoxidation Method 査読あり
H. Kobori, N. Takata, A. Yamasaki, T. Taniguchi and T. Shimizu
Proceedings of Asia-Pacific Engineering and Technology Conference 1012 - 1018 2017年
共著
担当区分:筆頭著者
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Two-Current Spin-Dependent Conduction in Polycrystalline LaMnO3 Produced under Oxygen Gas Flow 査読あり
H. Kobori, A. Hoshino, T. Taniguchi, T. Horie, Y. Naitoh, and T. Shimizu
AIP Conference Proceedings 1566 333 - 334 2014年
共著
担当区分:筆頭著者
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Magneto-transport study of magnetite (Fe3O4) nanoparticles between Au nanogap electrodes on surface-oxidized Si substrate 査読あり
H. Kobori, N. Takata, N. Fukutome and T. Shimizu
Journal of Magnetism and Magnetic Materials 331 88 - 91 2013年
共著
担当区分:筆頭著者
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Magnetoresistance Intensification of Fe3O4/BaTiO3 Nanoparticle-Composite-Sinter Produced by Low Temperature Heat Treatment 査読あり
H. Kobori, K. Uzimoto, A. Hoshino, A. Yamasak, A. Sugimura, T. Taniguchi, T. Horie, Y. Naitoh and T. Shimizu
The Journal of Superconductivity and Novel Magnetism 25 2809 - 2812 2012年
共著
担当区分:筆頭著者
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Intensified magneto-resistance by rapid thermal annealing in magnetite (Fe3O4) thin film on SiO2 glass substrate 査読あり
H. Kobori, K. Morii, A. Yamasaki, A. Sugimura, T. Taniguchi, T. Horie, Y. Naitoh, and T. Shimizu
Journal of Physics: Conference Series 400 1689 - 1692 2012年
共著
担当区分:筆頭著者
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Magneto-resistance enhancement due to self-hole-doping in LaMnO3 produced by low temperature heat treatment 査読あり
H. Kobori, A. Hoshino, A. Yamasaki, A. Sugimura, T. Taniguchi, T. Horie, Y. Naitoh, and T. Shimizu
Journal of Physics: Conference Series 400 1685 - 1688 2012年
共著
担当区分:筆頭著者
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Enhancement of negative magnetoresistance due to weak localization in In2O3 thin films on Si substrate 査読あり
A. Fujimoto, M. Kitamura, H. Kobori, A. Yamasaki, A. Sugimura, A. Ando, H. Kawanaka, Y. Naitoh, T. Shimizu
Physica E 42 1134 - 1137 2010年
共著
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Nanomanipulation of single nanoparticle using a carbon nanotube probe in a scanning electron microscope 査読あり
Hiroshi Suga, Yasuhisa Naitoh, Miyuki Tanaka, Masayo Horikawa, Hiromi Kobori, Tetsuo Shimizu
Applied Physics Express 2 ( 5 ) 2009年5月
共著
出版者・発行元:IOP PUBLISHING LTD
A novel method is presented for manipulation of a single nanoparticle using a carbon nanotube probe in a scanning electron microscope chamber. Nanomanipulation was achieved without dependence on the conductivity of the nanoparticle. In order to demonstrate the effectiveness of this technique, insulative Fe2O3 and conductive Fe3O 4 were arranged on a nanogap junction for measurement of the electrical conductivity. The result clearly showed the difference between the resistance of the two iron oxides. It is considered that this technique could be a milestone in the measurement of the physical properties of nanomaterials. © 2009 The Japan Society of Applied Physics.
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Appearance of Variable-Range-Hopping Conduction and Enhanced Spin Dependent Transport by Low Temperature Heat Treatment for Magnetite Nanoparticle Sinter(共著)
H. Kobori, K. Ohnishi, A. Sugimura and T. Taniguchi
Proceedings of the International Conference on Solid State Devices and Materials 2007 686 - 687 2007年
共著
担当区分:筆頭著者
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Localization and transport of type-ii excitons in spatially enhanced random potential for highly Si-doped GaAs/AlAs short-period-superlattices 査読あり
H. Kobori, A. Shigetani, I. Umezu, A. Sugimura
AIP Conference Proceedings 850 1520 - 1521 2006年
共著
Through the time-resolved photoluminescence measurements, we have studied the localization and transport of the type-II excitons in spatially random potential for highly Si-doped GaAs/AlAs short-period-superlattices (SPS's). The exciton transport analysis has been carried out according to Krivorotov et al. We have found that Si highly-doped into GaAs/AlAs SPS's causes the enhancement of the spatial fluctuation for type-II exciton. © 2006 American Institute of Physics.
DOI: 10.1063/1.2355281
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Unusual behavior on line-broadening of photoluminescence spectrum for type-ii excitons in Highly Si-doped GaAs/AlAs short-period-superlattices 査読あり
H. Kobori, A. Shigetani, I. Umezu, A. Sugimura
AIP Conference Proceedings 850 1522 - 1523 2006年
共著
Through the photoluminescence (PL) measurements, we have studied the temperature dependence of the linewidth of PL spectra for type-II excitons in highly Si-doped GaAs/AlAs short-period-superlattices (SPS's). In low temperature regions, we have observed the strong increase of the linewidth of PL spectra with the temperature, different from the case of undoped GaAs/AlAs SPS's. © 2006 American Institute of Physics.
DOI: 10.1063/1.2355282
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Magnetic-Field-induced Two-toThree-Dimensional Transition in Weak Localization and Weak Anti-Localization regimes for In2O3-X Thin Films:(共著) 査読あり
H. Kobori, N. Hatta, M. Kawaguchi and T. Ohyama
Physica E 12 641 - 645 2002年
共著
担当区分:筆頭著者
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Effects of resonant polarons and band nonparabolicity on cyclotron resonance in n−InP 査読あり
Hiromi Kobori, Tomoyuki Nomura, Tyuzi Ohyama
Physical Review B - Condensed Matter and Materials Physics 63 ( 11 ) 2001年
共著
We study the effects of resonant polarons and band nonparabolicity on the cyclotron resonance of conduction electrons in n−InP at 4.2 K in the far-infrared regions. By combining photo- and electric field-excitation techniques, we successfully separate and estimate the individual contributions of resonant polarons and band nonparabolicity to the resonance magnetic field of the cyclotron resonance. In analyses of the experimental results obtained by use of the electric field excitation technique, we take into consideration the energy redistribution of conduction electrons by the electric field excitation. Those resonance magnetic fields are revised to the values for conduction electrons populating the bottoms of Landau levels, on the basis of the experimental results obtained by use of the photoexcitation technique. The dispersion of the resonance magnetic field is fitted by theoretical calculations using the improved Wigner-Brillouin perturbation theories by Lindemann et al. and the three-band k·p method by Lax. The conduction-band-edge mass me0 and the polaron coupling constant α are used as fitting parameters. Excellent agreement between the experimental and theoretical results is obtained. We determine me0/mfe = 0.0788 (is the free-electron mass) and α = 0.12 for InP. © 2001 The American Physical Society.
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Linewidth study of electric dipole induced spin resonance in uniaxially stressed n-InSb for far-infrared region: Theoretical 査読あり
Ko Sugihara, Hiromi Kobori, Nobuteru Tsubouchi, Akira Sugio, Kenichi Fujii, Tyuzi Ohyama
Journal of the Physical Society of Japan 69 ( 9 ) 3084 - 3089 2000年9月
共著
Experimental investigation on electric dipole induced ESR in n-InSb was reported in the preceding paper (Experimental). Far-infrared laser with λ = 220 μm ∼ 84 μm and the samples with ND - NA = 1015 cm-3 were employed in the experiment. In this article we mainly focus our attentions to the origin of the observed linewidth. Linewidth is nearly constant at low temperature and increases with T above ∼20 K: 0.02 Tesla at 4.2 K and 0.1 Tesla at 60 K. From the relation of |g*|μBΔH = ℏ/T1, we obtain T1 ∼ 10-12 sec at T = 60 K, where |g*| = 44 is obtained from the absorption data for λ = 119 λm. Such a short relaxation time T1 cannot be expected from any spin-lattice relaxation process. Rashba-Sheka's Hamiltonian: H′ = δ0(E)σ · κ, σ: Pauli spin matrix, κx = kykxky - kzkxkz etc., is responsible for the linewidth broadening. This interaction stems from the lack of inversion symmetry in InSb. Linewidth calculation based on the Kubo-Tomita's theory qualitatively explains the temperature-dependence, the order of magnitude of the linewidth and the field dependence.
DOI: 10.1143/JPSJ.69.3084
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Linewidth Study of Electric Dipole Induced Spin Resonance in Uniaxially Stressed n-InSb in Far Infrared Regions: Experimental 査読あり
Hiromi Kobori, Akira Sugio, Nobuteru Tsubouchi, Kenichi Fujii, Tyuzi Ohyama, Ko Sugihara
Journal of the Physical Society of Japan 69 ( 7 ) 2315 - 2323 2000年7月
共著
We have carried out the linewidth measurements of the electric dipole induced spin resonance (EDSR) of conduction electrons in uniaxially stressed n-InSb in the far-infrared (FIR) regions. Our employed samples of n-InSb are highly doped with donors (6.0 × 1015 cm-3 and 8.5 × 1015 cm-3) and thus have metallic properties due to degenerate electrons. The linewiclths of the EDSR have been obtained as the functions of the magnetic field (2.10∼6.39 T), the temperature (4.2∼70 K) and the donor concentration. The main features of the experimental results are the followings: (1) It is found that the minimum of the linewidth appears on the magnetic field dependence at 4.2 K. (2) In the lower resonance magnetic field (2.10 T and 2.74 T) and lower temperature regions (T <∼ 20 K), we have recognized a slight reduction of the linewidth with the increasing of temperature. (3) For moderately high temperatures (T >∼ 20 K), the increment of the linewidth is found on our employed experimental conditions for all samples. (4) For the sample with higher donor concentration, the enhancement of the linewidth is also found in comparison with the sample with lower donor concentration. In this paper, the linewidth of the EDSR spectrum is mainly discussed in respect of the experimental results. The detailed theoretical discussion will be presented in the following paper by Sugihara et al.
DOI: 10.1143/JPSJ.69.2315
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Line-Width of Quantum Limit Cyclotron Resonance. I. Phonon Scatterings in Ge, Si, CdS and InSb 査読あり
Hiromi Kobori, Tyuji Ohyama, Eizo Otsuka
journal of the physical society of japan 59 ( 6 ) 2141 - 2163 1990年
共著
Studies of the Cyclotron Resonance Line-Width (CRLW) in the quantum limit have been made for phonon scatterings in basic semiconductors (Ge, Si, CdS and InSb). The acoustic deformation potential scattering has been examined for Ge and Si, while the acoustic piezo-electric scattering for CdS. The effect of the inelastic scattering is enhanced in the quantum limit. Furthermore, the spontaneous acoustic phonon emission is clearly affecting CRLW. Temperature dependences of CRLW for deformation potential and piezo-electric scatterings are similar to each other. Difference, however, arises in the magnetic field dependence. With regard to polar optical phonon scatterings, it has been confirmed for InSb that CRLW is dominated by the absorption part. © 1990, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.
DOI: 10.1143/JPSJ.59.2141