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Papers by Hironaga Uchida

Research paper thumbnail of Fabrication of Nano-Structures on NiFe Film by Anodization with Atomic Force Microscope

Journal of Magnetics, 2006

Research paper thumbnail of Time-resolved atomic-scale modification of silicon with a scanning tunneling microscope

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1994

Voltage pulses applied between the tip of a scanning tunneling microscope (STM) and a crystal sur... more Voltage pulses applied between the tip of a scanning tunneling microscope (STM) and a crystal surface often result in extraction or deposition of single atoms or clusters of atoms on the surface, which are detected by imaging the affected area with the STM after the pulse. Here, atomic-scale displacements of the STM tip during such surface modifications, due to structural changes occurring at the tunnel junction are studied. Using this technique, it is found that for the Si(111)7×7 surface and a W tip, modification during the pulse is field induced and not current induced, but that a considerable fraction of modification events occur shortly after a pulse. The ability to predict the type of modification from the direction of the tip displacement is investigated, and the applicability of this approach to high-speed nanofabrication is discussed.

Research paper thumbnail of PZT-Driven Micromagnetic Optical Devices

MRS Proceedings, 2003

ABSTRACTA magneto-optic spatial light modulator (MOSLM) driven by electric field is presented. Us... more ABSTRACTA magneto-optic spatial light modulator (MOSLM) driven by electric field is presented. Using finite element method simulation, the parameters of the MOSLM are decided including the 1 μm piezoelectric lead zirconate titanate (PZT)-based layer, the 200 nm bottom electrode, and the 8V electrical applied voltage. A flat surface magneto-optical bismuth-substituted iron garnet (Bi:YIG) based film having an array-pixels structure was created by a site-selected epitaxial method on a SGGG-based substrate. In order to avoid high temperature annealing process which may damage the Bi:YIG film, the PZT film was deposited by the aerosol deposition method (ADM) on the Bi:YIG film. By stress field induced by the PZT film to the Bi:YIG film with an external magnetic field, the pixels of the device were successfully switched.

Research paper thumbnail of Ｓｉ（１１１）７×７表面のＳｉアドアトムの結合エネルギーの差：ＳＴＭを用いた実験と理論計算による解析

Research paper thumbnail of Low-Temperature Deposition of Co/Pt Film with High-Perpendicular Magnetic Anisotropy by Layer Stacking Sputtering

IEEE Transactions on Magnetics, 2014

Research paper thumbnail of Development of fundamental components for amplification of magneto-surface-acoustic-waves in highly magnetostrictive metal films by means of electron bunching

MRS Proceedings, 2003

ABSTRACTIn a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an exte... more ABSTRACTIn a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an external magnetic field. We proposed amplification of MSAW with a hybrid structure of FeB amorphous film / InSb semiconductor thin film / LiNbO3 substrate, which is expected to compensate the attenuation of MSAW caused by eddy current loss. In the fabricated MSAW device having the FeB amorphous film with low coercivity and high magnetostrictive, the phase retardation of about 600 degree/cm at magnetic fields of ±300 Oe was obtained. The InSb thin film with a mobility of about 3.5×103 cm2/Vs was obtained by using annealing process. The results show possibility of the MSAW amplification.

Research paper thumbnail of Flat-surface magneto-optic spatial light modulator by using thermal infrared ray annealing

SPIE Proceedings, 2003

We demonstrated a flat-surface magneto-optic spatial light modulator (MOSLM) without physically i... more We demonstrated a flat-surface magneto-optic spatial light modulator (MOSLM) without physically isolated pixels and an external bias coil. The flat-surface MOSLM, which was fabricated by a simple process, was designed as a compact system with a high resolution and very low ...

Research paper thumbnail of Artificial Periodic Magnetic Structures for Photonic and High Frequency Micro-magnetic Devices

Journal of the Japan Society of Powder and Powder Metallurgy, 2011

Research paper thumbnail of Design of multimode EO waveguide for hologram optical switch

2007 Conference on Lasers and Electro-Optics - Pacific Rim, 2007

ABSTRACT The paper illustrates the structure of a multimode electro-optic ( EO ) waveguide, and w... more ABSTRACT The paper illustrates the structure of a multimode electro-optic ( EO ) waveguide, and we optimized a thickness d. The core of the multimode EO waveguide thickness d is 6 mum has a good performance to obtain the homogeneous electric field in the waveguide.

Research paper thumbnail of Analysis of Opal Template for Three Dimentional Magnetophotonic Crystals

INTERMAG 2006 - IEEE International Magnetics Conference, 2006

Periodic structures of dielectric materials in submicrometer are currently paid much attention as... more Periodic structures of dielectric materials in submicrometer are currently paid much attention as photonic crystals (PC) with photonic band gap (PBG), which prohibits light of specific wavelength from propagating in certain directions. We reported one-dimensional magnetophotonic crystals (1D-MPCs) constructed of dielectric multi layers and a magnetic defect layer obtained large enhancement of Faraday rotation in localized mode. On the other

Research paper thumbnail of Fabrication and magneto-optical responses of Au-Bi:YIG films

SPIE Proceedings, 2008

ABSTRACT We have studied magneto-optical responses of gold-bismuth-substituted yttrium iron garne... more ABSTRACT We have studied magneto-optical responses of gold-bismuth-substituted yttrium iron garnet (Au-Bi:YIG) composite films in which Au particles are embedded into Bi:YIG in two different ways. First type were samples in which planar arrays of Au particles were introduced into the middle of Bi:YIG films using a step-by-step sputtering technique. Second type were granular films fabricated using simultaneous co-sputtering of Au and Bi:YIG; in these films Au particles occupy positions inside composite films in a random way. Absorption bands associated with localized surface plasmon resonances (LSPRs) were observed in transmission spectra of films of both types. In the spectral range of LSPRs, samples of Au-array type exhibited larger Faraday rotation angles as compared with that for reference Bi:YIG films of the same thickness. However, given that the volume fraction of Au particles was nearly the same for both types, the enhancement of Faraday rotation for samples of Au-granular type was insignificantly altered. Experiments showed that of the primary importance is the role of the interfaces between Au particles and Bi:YIG. Theoretical estimations showed that, in samples of Au-granular type, air shells appeared between Au particles and Bi:YIG during fabrication. In fact, annealing needed for crystallization of Bi:YIG films is always accompanied with an expansion of their thicknesses.

Research paper thumbnail of Analysis of STM Images after Atom Extractions from the Si(111) 7 × 7 Unit Cell through a Cluster Model

The Journal of Physical Chemistry B, 1997

ABSTRACT Using an ab initio cluster model, we have investigated the electronic information contai... more ABSTRACT Using an ab initio cluster model, we have investigated the electronic information contained in scanning tunneling microscope (STM) images, which were obtained after atom extraction from the Si(111) 7 × 7 surface. Depending on the position of the created vacancy (corner versus center) and on the number of extracted atoms (single atom versus dimer), we obtain different density maps that permit us to propose a rationalization of the brightness of the spots that are observed in the corresponding experimental STM images. It can be understood by a localization of the surface state near the created atomic vacancy.

Research paper thumbnail of Study of adsorption of Al atom on Si(1 1 1)7 × 7 surface

Research paper thumbnail of Difference between staying and diffusing Si adsorbates on the Si(111)7×7 surface

Research paper thumbnail of Detection of Single Atom Extraction and Deposition Events during Nanolithographic Processing of Silicon with a Scanning Tunneling Microscope

Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences, 1993

Research paper thumbnail of Local hydride formation of the Si(111)-(7×7) surface by hydrogen atoms deposited from a scanning tunneling microscope tip

Physical Review Letters, 1994

Research paper thumbnail of Nonlinear Verdet law in magnetophotonic crystals: Interrelation between Faraday and Borrmann effects

Research paper thumbnail of LC filter-type magnetoimpedance sensors with multilayer film structure

physica status solidi (c), 2007

ABSTRACT We have investigated the basic characteristics and applicability of the LC high pass fil... more ABSTRACT We have investigated the basic characteristics and applicability of the LC high pass filter configuration for signal conditioning of the magnetoimpedance (MI) sensor. The MI sensor elements were fabricated through photolithography and lift-off process of CoZrNb/Au/CoZrNb multilayer, and the LC high pass filters were configured using the fabricated sensor elements and surface mount capacitors. To confirm the high frequency performance of the sensor elements, frequency dependence of the impedance was measured as function of external magnetic field using a network analyzer. The output increased to reach the peak value with increase of magnetic field to around 20 Oe, which was almost the same with the anisotropic field of the multilayer film pattern, and the measured maximum change ratio is 49%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Figures of merit of magneto‐optic spatial light modulators with magnetophotonic crystals

physica status solidi c, 2007

ABSTRACT This paper presents the simulated and measured results of two types of one dimensional m... more ABSTRACT This paper presents the simulated and measured results of two types of one dimensional magnetophotonic crystals (1-D MPC) with single cavity and dual cavity respectively for applcation to thin film type magneto-optic spatial light modulators (MOSLMs). The use of MPC is expected to be effective for thin film type MOSLM, because the apparent Faraday rotation is largely enhanced due to light localization in magnetic defect layer of MPC with a large number of periodic dielectric layers. The complex chracteristics of MPCs are discussed in this paper – Faraday rotation θF, transmittance T, and figure of merit F = T sin(2θF). It is key point of finding optimal structure of MPC for application of MOSLM to use F, because the T decreased with increase of k, while Faraday rotation θF increased, indicating that the enhancement of light modulation rate could be achieved by optimizing the figure of merit F defined by F ≈ T ·sin2θF. The maximum F = 13.7 was obtained in dual cavity MPC, while F = 12.5 was obtained in single cavity MPC. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Fabrication and swimming properties of micro‐machine coated with magnetite prepared by ferrite plating

physica status solidi (b), 2004

By the sterolithography technique and the ferrite plating, we have fabricated a magnetic micro‐ma... more By the sterolithography technique and the ferrite plating, we have fabricated a magnetic micro‐machine which coated Fe3O4. The sterolithography technique enables to form the spiral‐shape resinous templates and the ferrite plating enables to coat Fe3O4 uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We have verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As the machine coated with Fe3O4 has a biocompatibility, there is a possibility of medical micro‐robots which swim in human body for medical operations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Fabrication of Nano-Structures on NiFe Film by Anodization with Atomic Force Microscope

Journal of Magnetics, 2006

Research paper thumbnail of Time-resolved atomic-scale modification of silicon with a scanning tunneling microscope

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 1994

Voltage pulses applied between the tip of a scanning tunneling microscope (STM) and a crystal sur... more Voltage pulses applied between the tip of a scanning tunneling microscope (STM) and a crystal surface often result in extraction or deposition of single atoms or clusters of atoms on the surface, which are detected by imaging the affected area with the STM after the pulse. Here, atomic-scale displacements of the STM tip during such surface modifications, due to structural changes occurring at the tunnel junction are studied. Using this technique, it is found that for the Si(111)7×7 surface and a W tip, modification during the pulse is field induced and not current induced, but that a considerable fraction of modification events occur shortly after a pulse. The ability to predict the type of modification from the direction of the tip displacement is investigated, and the applicability of this approach to high-speed nanofabrication is discussed.

Research paper thumbnail of PZT-Driven Micromagnetic Optical Devices

MRS Proceedings, 2003

ABSTRACTA magneto-optic spatial light modulator (MOSLM) driven by electric field is presented. Us... more ABSTRACTA magneto-optic spatial light modulator (MOSLM) driven by electric field is presented. Using finite element method simulation, the parameters of the MOSLM are decided including the 1 μm piezoelectric lead zirconate titanate (PZT)-based layer, the 200 nm bottom electrode, and the 8V electrical applied voltage. A flat surface magneto-optical bismuth-substituted iron garnet (Bi:YIG) based film having an array-pixels structure was created by a site-selected epitaxial method on a SGGG-based substrate. In order to avoid high temperature annealing process which may damage the Bi:YIG film, the PZT film was deposited by the aerosol deposition method (ADM) on the Bi:YIG film. By stress field induced by the PZT film to the Bi:YIG film with an external magnetic field, the pixels of the device were successfully switched.

Research paper thumbnail of Ｓｉ（１１１）７×７表面のＳｉアドアトムの結合エネルギーの差：ＳＴＭを用いた実験と理論計算による解析

Research paper thumbnail of Low-Temperature Deposition of Co/Pt Film with High-Perpendicular Magnetic Anisotropy by Layer Stacking Sputtering

IEEE Transactions on Magnetics, 2014

Research paper thumbnail of Development of fundamental components for amplification of magneto-surface-acoustic-waves in highly magnetostrictive metal films by means of electron bunching

MRS Proceedings, 2003

ABSTRACTIn a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an exte... more ABSTRACTIn a magneto-surface-acoustic-wave (MSAW) device, phase velocity is controlled by an external magnetic field. We proposed amplification of MSAW with a hybrid structure of FeB amorphous film / InSb semiconductor thin film / LiNbO3 substrate, which is expected to compensate the attenuation of MSAW caused by eddy current loss. In the fabricated MSAW device having the FeB amorphous film with low coercivity and high magnetostrictive, the phase retardation of about 600 degree/cm at magnetic fields of ±300 Oe was obtained. The InSb thin film with a mobility of about 3.5×103 cm2/Vs was obtained by using annealing process. The results show possibility of the MSAW amplification.

Research paper thumbnail of Flat-surface magneto-optic spatial light modulator by using thermal infrared ray annealing

SPIE Proceedings, 2003

We demonstrated a flat-surface magneto-optic spatial light modulator (MOSLM) without physically i... more We demonstrated a flat-surface magneto-optic spatial light modulator (MOSLM) without physically isolated pixels and an external bias coil. The flat-surface MOSLM, which was fabricated by a simple process, was designed as a compact system with a high resolution and very low ...

Research paper thumbnail of Artificial Periodic Magnetic Structures for Photonic and High Frequency Micro-magnetic Devices

Journal of the Japan Society of Powder and Powder Metallurgy, 2011

Research paper thumbnail of Design of multimode EO waveguide for hologram optical switch

2007 Conference on Lasers and Electro-Optics - Pacific Rim, 2007

ABSTRACT The paper illustrates the structure of a multimode electro-optic ( EO ) waveguide, and w... more ABSTRACT The paper illustrates the structure of a multimode electro-optic ( EO ) waveguide, and we optimized a thickness d. The core of the multimode EO waveguide thickness d is 6 mum has a good performance to obtain the homogeneous electric field in the waveguide.

Research paper thumbnail of Analysis of Opal Template for Three Dimentional Magnetophotonic Crystals

INTERMAG 2006 - IEEE International Magnetics Conference, 2006

Periodic structures of dielectric materials in submicrometer are currently paid much attention as... more Periodic structures of dielectric materials in submicrometer are currently paid much attention as photonic crystals (PC) with photonic band gap (PBG), which prohibits light of specific wavelength from propagating in certain directions. We reported one-dimensional magnetophotonic crystals (1D-MPCs) constructed of dielectric multi layers and a magnetic defect layer obtained large enhancement of Faraday rotation in localized mode. On the other

Research paper thumbnail of Fabrication and magneto-optical responses of Au-Bi:YIG films

SPIE Proceedings, 2008

ABSTRACT We have studied magneto-optical responses of gold-bismuth-substituted yttrium iron garne... more ABSTRACT We have studied magneto-optical responses of gold-bismuth-substituted yttrium iron garnet (Au-Bi:YIG) composite films in which Au particles are embedded into Bi:YIG in two different ways. First type were samples in which planar arrays of Au particles were introduced into the middle of Bi:YIG films using a step-by-step sputtering technique. Second type were granular films fabricated using simultaneous co-sputtering of Au and Bi:YIG; in these films Au particles occupy positions inside composite films in a random way. Absorption bands associated with localized surface plasmon resonances (LSPRs) were observed in transmission spectra of films of both types. In the spectral range of LSPRs, samples of Au-array type exhibited larger Faraday rotation angles as compared with that for reference Bi:YIG films of the same thickness. However, given that the volume fraction of Au particles was nearly the same for both types, the enhancement of Faraday rotation for samples of Au-granular type was insignificantly altered. Experiments showed that of the primary importance is the role of the interfaces between Au particles and Bi:YIG. Theoretical estimations showed that, in samples of Au-granular type, air shells appeared between Au particles and Bi:YIG during fabrication. In fact, annealing needed for crystallization of Bi:YIG films is always accompanied with an expansion of their thicknesses.

Research paper thumbnail of Analysis of STM Images after Atom Extractions from the Si(111) 7 × 7 Unit Cell through a Cluster Model

The Journal of Physical Chemistry B, 1997

ABSTRACT Using an ab initio cluster model, we have investigated the electronic information contai... more ABSTRACT Using an ab initio cluster model, we have investigated the electronic information contained in scanning tunneling microscope (STM) images, which were obtained after atom extraction from the Si(111) 7 × 7 surface. Depending on the position of the created vacancy (corner versus center) and on the number of extracted atoms (single atom versus dimer), we obtain different density maps that permit us to propose a rationalization of the brightness of the spots that are observed in the corresponding experimental STM images. It can be understood by a localization of the surface state near the created atomic vacancy.

Research paper thumbnail of Study of adsorption of Al atom on Si(1 1 1)7 × 7 surface

Research paper thumbnail of Difference between staying and diffusing Si adsorbates on the Si(111)7×7 surface

Research paper thumbnail of Detection of Single Atom Extraction and Deposition Events during Nanolithographic Processing of Silicon with a Scanning Tunneling Microscope

Proceedings of the Japan Academy. Ser. B: Physical and Biological Sciences, 1993

Research paper thumbnail of Local hydride formation of the Si(111)-(7×7) surface by hydrogen atoms deposited from a scanning tunneling microscope tip

Physical Review Letters, 1994

Research paper thumbnail of Nonlinear Verdet law in magnetophotonic crystals: Interrelation between Faraday and Borrmann effects

Research paper thumbnail of LC filter-type magnetoimpedance sensors with multilayer film structure

physica status solidi (c), 2007

ABSTRACT We have investigated the basic characteristics and applicability of the LC high pass fil... more ABSTRACT We have investigated the basic characteristics and applicability of the LC high pass filter configuration for signal conditioning of the magnetoimpedance (MI) sensor. The MI sensor elements were fabricated through photolithography and lift-off process of CoZrNb/Au/CoZrNb multilayer, and the LC high pass filters were configured using the fabricated sensor elements and surface mount capacitors. To confirm the high frequency performance of the sensor elements, frequency dependence of the impedance was measured as function of external magnetic field using a network analyzer. The output increased to reach the peak value with increase of magnetic field to around 20 Oe, which was almost the same with the anisotropic field of the multilayer film pattern, and the measured maximum change ratio is 49%. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Figures of merit of magneto‐optic spatial light modulators with magnetophotonic crystals

physica status solidi c, 2007

ABSTRACT This paper presents the simulated and measured results of two types of one dimensional m... more ABSTRACT This paper presents the simulated and measured results of two types of one dimensional magnetophotonic crystals (1-D MPC) with single cavity and dual cavity respectively for applcation to thin film type magneto-optic spatial light modulators (MOSLMs). The use of MPC is expected to be effective for thin film type MOSLM, because the apparent Faraday rotation is largely enhanced due to light localization in magnetic defect layer of MPC with a large number of periodic dielectric layers. The complex chracteristics of MPCs are discussed in this paper – Faraday rotation θF, transmittance T, and figure of merit F = T sin(2θF). It is key point of finding optimal structure of MPC for application of MOSLM to use F, because the T decreased with increase of k, while Faraday rotation θF increased, indicating that the enhancement of light modulation rate could be achieved by optimizing the figure of merit F defined by F ≈ T ·sin2θF. The maximum F = 13.7 was obtained in dual cavity MPC, while F = 12.5 was obtained in single cavity MPC. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Fabrication and swimming properties of micro‐machine coated with magnetite prepared by ferrite plating

physica status solidi (b), 2004

By the sterolithography technique and the ferrite plating, we have fabricated a magnetic micro‐ma... more By the sterolithography technique and the ferrite plating, we have fabricated a magnetic micro‐machine which coated Fe3O4. The sterolithography technique enables to form the spiral‐shape resinous templates and the ferrite plating enables to coat Fe3O4 uniformly onto these templates from an aqueous solution. The total machine weight is light because a resin of the template body is almost the same density as water. We have verified that the machines swim freely and wirelessly in water by applying a rotational magnetic field. As the machine coated with Fe3O4 has a biocompatibility, there is a possibility of medical micro‐robots which swim in human body for medical operations. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)