The Experts below are selected from a list of 108657 Experts worldwide ranked by ideXlab platform
Mikhail Kostylev - One of the best experts on this subject based on the ideXlab platform.
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brillouin light Scattering Spectroscopy of parametrically excited dipole exchange magnons
Physical Review B, 2012Co-Authors: Alexander A. Serga, C W Sandweg, Matthias B Jungfleisch, Peter Kopietz, A. Kreisel, Burkard Hillebrands, Vitaliy I. Vasyuchka, Mikhail KostylevAbstract:The spectral distribution of parametrically excited dipole-exchange magnons in an in-plane magnetized epitaxial film of yttrium-iron garnet was studied by means of frequency- and wavevector-resolved Brillouin light Scattering Spectroscopy. The experiment was performed in a parallel pumping geometry where an exciting microwave magnetic field was parallel to the magnetizing field. It was found that for both dipolar and exchange spectral areas parallel pumping excites the lowest volume magnon modes propagating in the film plane perpendicularly to the magnetization direction. In order to interpret the experimental observations, we used a microscopic Heisenberg model that includes exchange as well as dipole-dipole interactions to calculate the magnon spectrum and construct the eigenstates. As proven in our calculations, the observed magnons are characterized by having the highest possible ellipticity of precession which suggests the lowest threshold of parametric generation. Applying different pumping powers we observe modifications in the magnon spectrum that are described theoretically by a softening of the spin stiffness.
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brillouin light Scattering Spectroscopy of parametrically excited dipole exchange magnons
Physical Review B, 2012Co-Authors: Alexander A. Serga, C W Sandweg, Matthias B Jungfleisch, Peter Kopietz, Vitaliy I. Vasyuchka, B Hillebrands, Andreas Kreisel, Mikhail KostylevAbstract:The spectral distribution of parametrically excited dipole-exchange magnons in an in-plane magnetized epitaxial film of yttrium-iron garnet was studied by means of frequency- and wavevector-resolved Brillouin light Scattering Spectroscopy. The experiment was performed in a parallel pumping geometry, where an exciting microwave magnetic field was parallel to the magnetizing field. It was found that for both dipolar and exchange spectral areas parallel pumping excites the lowest volume magnon modes propagating in the film plane perpendicularly to the magnetization direction. No excitation of the high-order volume modes has been registered. In order to interpret the experimental observations, we used a microscopic Heisenberg model that includes exchange as well as dipole-dipole interactions to calculate the magnon spectrum and construct the eigenstates. As proven in our calculations, the observed magnons are characterized by having the highest possible ellipticity of precession, which suggests the lowest threshold of parametric generation. Applying different pumping powers we observe modifications in the magnon spectrum that are described theoretically by a softening of the spin stiffness.
Yasushi Yamauchi - One of the best experts on this subject based on the ideXlab platform.
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element selective spin polarization analysis of surfaces by spin polarized ion Scattering Spectroscopy
Surface Science, 2010Co-Authors: Taku Suzuki, H. Kuwahara, Yasushi YamauchiAbstract:We discuss the validity of surface spin polarization analysis with element selectivity using spin-polarized ion Scattering Spectroscopy (SP-ISS). We examined the control of the incident 4He+ spins and successfully conducted magnetic hysteresis measurement on an Fe(100) surface. The spin polarization of the Fe(100) surface exposed to O2 atmosphere measured by spin-polarized ion neutralization Spectroscopy was consistent with that reported by spin-polarized metastable de-excitation Spectroscopy. The element selectivity of SP-ISS is discussed in terms of ion neutralization, re-ionization, and multiple Scattering.
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spin polarized ion Scattering Spectroscopy of ccl4 adsorption on fe 001 surfaces
Surface Science, 2008Co-Authors: Shigeru Entani, Toshinori Suzuki, Yasushi YamauchiAbstract:Abstract The interaction of CCl 4 molecules with Fe(0 0 1) surfaces was investigated by spin-polarized ion Scattering Spectroscopy (SP-ISS). It was observed that CCl 4 molecules adsorb dissociatively on the surface at ambient temperature (∼290 K), and consequently, iron and chlorine were major surface constituents. It was found that the chlorine adatoms are located atop of iron atoms of the second surface layer (hollow sites of the surface). It is indicated that the spin state of iron atoms at the surface is not affected by exposure to a CCl 4 atmosphere, while almost no spin is induced in the chlorine adatoms. Similar behavior is observed in the spin states of iron and chlorine on an oxygen preadsorbed-Fe(0 0 1) surface. The difference in the spin states of iron and chlorine clarifies the local property of the incidence ion neutralization and element selectivity of SP-ISS in this CCl 4 /Fe system.
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spin polarized ion Scattering Spectroscopy as a novel analytical method of magnetic structure at outermost surfaces
Surface Science, 2008Co-Authors: Taku Suzuki, Yasushi YamauchiAbstract:Abstract We developed spin-polarized ion Scattering Spectroscopy (SP-ISS). In SP-ISS, spin-polarized 4 He + ions are projected onto a sample surface, and the kinetic energy of scattered ions, which survive in neutralization, are analyzed. We observed that scattered ion yield depends on spin of the incident He + ions on an Fe(1 0 0) surface exposed to an oxygen atmosphere. Furthermore, we revealed that the spin dependence of scattered ion yield reflects the spin state of target atoms. Thus, SP-ISS may be capable of analyzing the spin state of outermost surfaces with element selectivity.
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development of spin polarized ion Scattering Spectroscopy
Analytical Sciences, 2008Co-Authors: Taku Suzuki, Yasushi YamauchiAbstract:Spin-polarized ion Scattering Spectroscopy using an electron-spin-polarized 4 He + ion beam was developed as a novel analytical method of the element selective spin state at outermost surfaces. Spin-polarized He + ions were generated from the Penning ionization of metastable He 2 3 S 1 atoms (He*), which were spin-polarized by optical pumping (OP). The spin polarization of He* (P He *) was observed to be the highest with an OP radiation density of about 0.05 W cm -2 , and a further increase of the OP radiation density reduced P He* . This decrease of P He * is attributed to imperfect polarization of the OP radiation, hence optimization of the OP radiation density is essential to obtain He + ions with high spin polarization. As a result of this optimization, we successfully observed the spin dependence of the scattered He + ion yield on an Fe(100) surface exposed to an oxygen atmosphere.
Mamoru Yoshimoto - One of the best experts on this subject based on the ideXlab platform.
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in situ analysis of the room temperature epitaxial growth of ceo2 ultrathin films on si 111 by coaxial impact collision ion Scattering Spectroscopy
Applied Physics Letters, 2001Co-Authors: M Furusawa, J Tashiro, Atsushi Sasaki, Kiyomi Nakajima, Masahiro Takakura, Toyohiro Chikyow, P Ahmet, Mamoru YoshimotoAbstract:The room-temperature epitaxial growth of CeO2 films on Si(111) substrates was examined in situ by combined use of a coaxial impact-collision ion Scattering Spectroscopy (CAICISS) and the laser molecular beam epitaxy (laser MBE). It was found that the crystal quality of CeO2 ultrathin films (∼3 nm thick) as-grown in UHV (∼10−9 Torr) could be improved remarkably by a few minutes of O2 gas exposure (∼10−5 Torr) at room temperature. A three-fold symmetry in the Ce signal intensity of azimuth rotational CAICISS spectra, which exhibited the type-B epitaxial growth ([110]CeO2‖[110]Si), was observed for the films thicker than about 1 nm.
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structural analysis of inxga1 xn single quantum wells by coaxial impact collision ion Scattering Spectroscopy
Applied Physics Letters, 2000Co-Authors: Masashi Sumiya, M Furusawa, Shigefusa F. Chichibu, Shuji Nakamura, K Mizuno, Mamoru YoshimotoAbstract:The structures of InxGa1−xN single quantum wells (SQWs) on 3-μm-thick GaN layer for the ultraviolet, blue, and green light-emitting devices were investigated by coaxial-impact collision ion Scattering Spectroscopy (CAICISS). The possibility that CAICISS could analyze structural fluctuation of the ternary system like InxGa1−xN was demonstrated. It was found that In incorporated into InGaN SQWs occupied the substitutional site of Ga atom having Ga-face (+c) polarity.
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analysis of the polar direction of gan film growth by coaxial impact collision ion Scattering Spectroscopy
Applied Physics Letters, 1999Co-Authors: Masashi Sumiya, Miyoko Tanaka, Kohji Ohtsuka, T Ohnishi, I Ohkubo, Hideomi Koinuma, Shunro Fuke, Mamoru Yoshimoto, Megumi KawasakiAbstract:Nondestructive determination of the polarity of GaN has been achieved by the use of coaxial impact-collision ion Scattering Spectroscopy analysis. The polarity of a GaN film with a smooth surface on non-nitrided c-plane sapphire was identified (0001) (Ga face; +c). GaN films with a 20 nm buffer layer on nitrided sapphire had (0001) (N face; −c) polarity and a hexagonal faceted surface. The influence of both the buffer layer and of substrate nitridation on the polarity of wurtzite {0001} GaN films deposited by two-step metal organic chemical vapor deposition (MOCVD) has been investigated. The polarity of the buffer layer on a nitrided sapphire substrate was altered by varying its thickness or the annealing time. It was found that the polarity of the GaN film is determined by the polarity of the annealed buffer layer; MOCVD-GaN films on buffer layers with +c and −c polarity have either +c (smooth surface) or −c (hexagonal facet) polarity, respectively.
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coaxial impact collision ion Scattering Spectroscopy analysis of zno thin films and single crystals
Materials Science and Engineering B-advanced Functional Solid-state Materials, 1998Co-Authors: T Ohnishi, Akira Ohtomo, Megumi Kawasaki, Mamoru Yoshimoto, I Ohkuboa, Hideomi KoinumaAbstract:Abstract Coaxial impact-collision ion Scattering Spectroscopy (CAICISS) was employed to analyze the surface structure of ZnO single crystals and thin films with various thickness. Epitaxial ZnO films grown on sapphire (α-Al2O3) (0001) by laser molecular beam epitaxy was found to choose the [0001] growth direction (the (0001) O face termination) among asymmetric c-axis directions of wurtzite structure by comparing the spectra and their incident angle dependences of the films with those of well-defined (0001) Zn face and (0001) O face surfaces of bulk single crystals. The incident angle dependences of Zn signal intensity for single crystals and thick (>10 nm) films can be well fitted with the simulated curves without taking reconstruction of the surface into account. However, the CAICISS results for the very thin film (2 nm) showed considerable deviation from the data of single crystals, suggesting the existence of the distorted region during the initial growth stage induced by the large lattice mismatch between ZnO and sapphire (18%). The growth mechanism and preferential [0001] growth direction of ZnO are discussed based on preferential tetrahedral bonding between Zn and O atoms on the sapphire surface.
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in situ determination of the terminating layer of la0 7sr0 3mno3 thin films using coaxial impact collision ion Scattering Spectroscopy
Applied Physics Letters, 1998Co-Authors: Mamoru Yoshimoto, Hidenori Maruta, T Ohnishi, Kenji Sasaki, Hideomi KoinumaAbstract:In situ analysis of the terminating atomic plane of c-axis oriented La0.7Sr0.3MnO3 thin films grown epitaxially on SrTiO3(100) substrate by laser molecular beam epitaxy has been carried out employing coaxial impact-collision ion Scattering Spectroscopy (CAICISS). The CAICISS time-of-flight spectroscopic studies reveal that the (001) surface of c-axis oriented La0.7Sr0.3MnO3 thin films is predominantly terminated with MnO2 plane. The azimuth rotational CAICISS measurements show a fourfold symmetry in the surface atom alignments establishing the square lattice structure of the terminating plane.
Taku Suzuki - One of the best experts on this subject based on the ideXlab platform.
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low energy ion Scattering Spectroscopy and reflection high energy electron diffraction of native oxides on gan 0001
Japanese Journal of Applied Physics, 2017Co-Authors: Yoshihiro Irokawa, Kazuya Yuge, Koji Kimoto, Toshihide Nabatame, Taku Suzuki, T Ohnishi, Kazutaka Mitsuishi, Yasuo KoideAbstract:We investigated native oxides on GaN(0001) wafers by low-energy ion Scattering Spectroscopy (LEIS) and reflection high-energy electron diffraction (RHEED) simultaneously. As a result, azimuthal angle-resolved LEIS revealed that the surface structure of the native oxide with a thickness of ~1.1 nm showed a low sixfold symmetry. Moreover, the RHEED patterns of native oxides on GaN showed (1 × 1) surface spots, reflecting the same lattice constant of GaN regardless of the glancing angle of the incident beam. The obtained results suggest that native oxides on GaN(0001) could be either e-Ga2O3, γ-Ga2O3(111), or their mixture, with lattice-matched structures.
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element selective spin polarization analysis of surfaces by spin polarized ion Scattering Spectroscopy
Surface Science, 2010Co-Authors: Taku Suzuki, H. Kuwahara, Yasushi YamauchiAbstract:We discuss the validity of surface spin polarization analysis with element selectivity using spin-polarized ion Scattering Spectroscopy (SP-ISS). We examined the control of the incident 4He+ spins and successfully conducted magnetic hysteresis measurement on an Fe(100) surface. The spin polarization of the Fe(100) surface exposed to O2 atmosphere measured by spin-polarized ion neutralization Spectroscopy was consistent with that reported by spin-polarized metastable de-excitation Spectroscopy. The element selectivity of SP-ISS is discussed in terms of ion neutralization, re-ionization, and multiple Scattering.
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spin polarized ion Scattering Spectroscopy as a novel analytical method of magnetic structure at outermost surfaces
Surface Science, 2008Co-Authors: Taku Suzuki, Yasushi YamauchiAbstract:Abstract We developed spin-polarized ion Scattering Spectroscopy (SP-ISS). In SP-ISS, spin-polarized 4 He + ions are projected onto a sample surface, and the kinetic energy of scattered ions, which survive in neutralization, are analyzed. We observed that scattered ion yield depends on spin of the incident He + ions on an Fe(1 0 0) surface exposed to an oxygen atmosphere. Furthermore, we revealed that the spin dependence of scattered ion yield reflects the spin state of target atoms. Thus, SP-ISS may be capable of analyzing the spin state of outermost surfaces with element selectivity.
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development of spin polarized ion Scattering Spectroscopy
Analytical Sciences, 2008Co-Authors: Taku Suzuki, Yasushi YamauchiAbstract:Spin-polarized ion Scattering Spectroscopy using an electron-spin-polarized 4 He + ion beam was developed as a novel analytical method of the element selective spin state at outermost surfaces. Spin-polarized He + ions were generated from the Penning ionization of metastable He 2 3 S 1 atoms (He*), which were spin-polarized by optical pumping (OP). The spin polarization of He* (P He *) was observed to be the highest with an OP radiation density of about 0.05 W cm -2 , and a further increase of the OP radiation density reduced P He* . This decrease of P He * is attributed to imperfect polarization of the OP radiation, hence optimization of the OP radiation density is essential to obtain He + ions with high spin polarization. As a result of this optimization, we successfully observed the spin dependence of the scattered He + ion yield on an Fe(100) surface exposed to an oxygen atmosphere.
Alexander A. Serga - One of the best experts on this subject based on the ideXlab platform.
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brillouin light Scattering Spectroscopy of parametrically excited dipole exchange magnons
Physical Review B, 2012Co-Authors: Alexander A. Serga, C W Sandweg, Matthias B Jungfleisch, Peter Kopietz, A. Kreisel, Burkard Hillebrands, Vitaliy I. Vasyuchka, Mikhail KostylevAbstract:The spectral distribution of parametrically excited dipole-exchange magnons in an in-plane magnetized epitaxial film of yttrium-iron garnet was studied by means of frequency- and wavevector-resolved Brillouin light Scattering Spectroscopy. The experiment was performed in a parallel pumping geometry where an exciting microwave magnetic field was parallel to the magnetizing field. It was found that for both dipolar and exchange spectral areas parallel pumping excites the lowest volume magnon modes propagating in the film plane perpendicularly to the magnetization direction. In order to interpret the experimental observations, we used a microscopic Heisenberg model that includes exchange as well as dipole-dipole interactions to calculate the magnon spectrum and construct the eigenstates. As proven in our calculations, the observed magnons are characterized by having the highest possible ellipticity of precession which suggests the lowest threshold of parametric generation. Applying different pumping powers we observe modifications in the magnon spectrum that are described theoretically by a softening of the spin stiffness.
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brillouin light Scattering Spectroscopy of parametrically excited dipole exchange magnons
Physical Review B, 2012Co-Authors: Alexander A. Serga, C W Sandweg, Matthias B Jungfleisch, Peter Kopietz, Vitaliy I. Vasyuchka, B Hillebrands, Andreas Kreisel, Mikhail KostylevAbstract:The spectral distribution of parametrically excited dipole-exchange magnons in an in-plane magnetized epitaxial film of yttrium-iron garnet was studied by means of frequency- and wavevector-resolved Brillouin light Scattering Spectroscopy. The experiment was performed in a parallel pumping geometry, where an exciting microwave magnetic field was parallel to the magnetizing field. It was found that for both dipolar and exchange spectral areas parallel pumping excites the lowest volume magnon modes propagating in the film plane perpendicularly to the magnetization direction. No excitation of the high-order volume modes has been registered. In order to interpret the experimental observations, we used a microscopic Heisenberg model that includes exchange as well as dipole-dipole interactions to calculate the magnon spectrum and construct the eigenstates. As proven in our calculations, the observed magnons are characterized by having the highest possible ellipticity of precession, which suggests the lowest threshold of parametric generation. Applying different pumping powers we observe modifications in the magnon spectrum that are described theoretically by a softening of the spin stiffness.
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wide range wavevector selectivity of magnon gases in brillouin light Scattering Spectroscopy
Review of Scientific Instruments, 2010Co-Authors: C W Sandweg, Matthias B Jungfleisch, Alexander A. Serga, Vitaliy I. Vasyuchka, P Clausen, Helmut Schultheiss, B Hillebrands, Andreas Kreisel, Peter KopietzAbstract:Brillouin light Scattering Spectroscopy is a powerful technique for the study of fast magnetization dynamics with both frequency and wavevector resolutions. Here, we report on a distinct improvement of this spectroscopic technique toward two-dimensional wide-range wavevector selectivity in a backward Scattering geometry. Spin-wave wavevectors oriented perpendicularly to the bias magnetic field are investigated by tilting the sample within the magnet gap. Wavevectors which are oriented parallel to the applied magnetic field are analyzed by turning the entire setup, including the magnet system. The setup features a wide selectivity of wavevectors up to 2.04×105 rad/cm for both orientations, and allows selecting and measuring wavevectors of dipole- and exchange-dominated spin waves of any orientation to the magnetization simultaneously.
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wide range wavevector selectivity of magnon gases in brillouin light Scattering Spectroscopy
arXiv: Instrumentation and Detectors, 2010Co-Authors: C W Sandweg, Matthias B Jungfleisch, Alexander A. Serga, Vitaliy I. Vasyuchka, P Clausen, Helmut Schultheiss, B Hillebrands, Andreas Kreisel, Peter KopietzAbstract:Brillouin light Scattering Spectroscopy is a powerful technique for the study of fast magnetization dynamics with both frequency- and wavevector resolution. Here, we report on a distinct improvement of this spectroscopic technique towards two-dimensional wide-range wavevector selectivity in a backward Scattering geometry. Spin-wave wavevectors oriented perpendicular to the bias magnetic field are investigated by tilting the sample within the magnet gap. Wavevectors which are oriented parallel to the applied magnetic field are analyzed by turning the entire setup, including the magnet system. The setup features a wide selectivity of wavevectors up to 2.04\cdot 10E5 rad/cm for both orientations, and allows selecting and measuring wavevectors of dipole- and exchange-dominated spin waves of any orientation to the magnetization simultaneously.
