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  • 1
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of medicinal chemistry 11 (1968), S. 1246-1248 
    ISSN: 1520-4804
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5843-5849 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report magnetoresistance in Cr-Fe bulk alloys and its variations associated with the microstructure change due to the phase decomposition. Large negative magnetoresistance (MR) is observed in the as-quenched Cr-Fe bulk alloy at liquid helium temperature, but not at room temperature. This is attributed to the spin cluster glass in the homogeneous solid solution. A unique feature of the MR in these homogenous alloys is that it does not saturate even in the presence of very high magnetic fields. However, such MR behavior changes when ferromagnetic particles precipitate by annealing. A lower degree of compositional fluctuation of Fe progresses by annealing the alloy at 773 K for 400 h and then a higher degree of decomposition occurs after a prolonged aging for 2600 h. In the annealed specimens, MR is observed even at room temperature. The MR change becomes more prominent at a lower field region, since ferromagnetic particles precipitate from the solid solution. The degree of the phase decomposition of the Cr-Fe solid solution is quantitatively evaluated by the atom probe analysis, and the origin of the MR dependence on the annealing conditions is discussed. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4733-4733 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Giant magnetoresistance (GMR, large negative and isotropic magnetoresistance) arising from a spin-dependent tunneling effect has been found in metal–nonmetal granular systems exhibiting extremely high electrical resistivities. These granular materials are reactively sputtered Co–(Al, Si)–O and Fe–Mg–O thin films, having a two phase nanostructure consisting of the Co (or Fe) rich metallic and magnetic grains and the Al (or Si,Mg) oxide narrow intergrains. These films possess large specific electrical resistivities(ρ0) of 104–106 μΩ cm at room temperature, and show remarkable magnetoresistance (Δρ/ρ0) whose values are about 8% in maximum at room temperature and at about 10 kOe of applied magnetic field. With decreasing temperature, Δρ/ρ0 and ρ0 increase. The temperature dependence of ρ0 can be expressed in terms of log ρ0∝T−1.2, and the electrical current versus applied electrical voltage does not follow the ohmic low. We consider that a spin- dependent tunneling conductance in the path of magnetic grains–nonmetallic intergrains–magnetic grains is responsible for the observed GMRs accompanying high electrical resistivities. The details of these transport properties and the related magnetization and structural properties will be presented. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6790-6792 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have observed large negative magnetoresistance (MR) in Cr-Fe heterogeneous alloy films sputter deposited on heated substrates. The largest MR, 37.3% at 4.2 K and 14 T, appears around the Fe concentration of 20 at. %. While a large substrate temperature dependence of MR is observed when the Fe concentration is lower than 20 at. %, MR does not vary noticeably with changes in the substrate temperature when Fe concentration exceeds 20 at. %.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5130-5135 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The structure and properties of Co–N and Co–O based films, prepared by rf magnetron reactive sputtering using nitrogen or oxygen and argon gases, have been studied. Transmission electron microscopy (TEM) observation reveals that each Co–(Al or Si)–(N or O) film is a typical film with granular structure, with grain size less than 5 nm. It is found by micro-focused energy-dispersive x-ray and electron energy loss spectroscopy analysis that the grains are mainly composed of Co and the intergranular regions are ceramics of N or O. In Co–N based films, soft magnetic properties are found in both Si and Al containing films over a wide range of film preparation conditions and compositions. Only the films with Al show soft magnetic properties in Co–O based films, which have ρ of 500–1000 μΩ cm, Hk of about 80 Oe and Bs of about 10 kG. By adding about 10 at. % Pd, the soft magnetic properties and Hk of Co–O based films are significantly improved, with Hk more than 180 Oe. These films exhibit a remarkable constant frequency response of the permeability up to around 500 MHz, which is approximately explained by the Landau–Lifshitz formula. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 1637-1643 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Multilayered Mo/Si thin films have been prepared by dual rf-magnetron sputtering technique, and the superconducting transition temperature Tc and the upper critical field Hc2 have been examined by resistance measurements. X-ray diffractometry shows that for the modulation wavelength λ shorter than 3 nm both Mo and Si sublayers are amorphous, while for λ longer than 3 nm, crystalline bcc structures appear in Mo sublayers. The λ dependence of Tc of the multilayer films with equal sublayer thickness shows that Tc takes a maximum value of 6.1 K for λ=2.3 nm and approaches the Tc value of amorphous Mo56Si44 in the small λ limit. The superconductivity of the multilayers has been confirmed to result from amorphous MoSi phase formed in the interfacial region of the sublayers. The thickness of the superconducting amorphous layer is estimated to be about 3 nm from the λ dependence of Tc and from the result of the anisotropy of Hc2 . Keeping the Mo sublayer thickness less than 2.4 nm to suppress the appearance of the crystalline Mo and increasing the Si sublayer thickness to reduce the interlayer Josephson coupling, an ideal quasi-two-dimensional superconductor with dHc2(parallel) /dT as high as 180 kOe/K has been realized.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6331-6333 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have investigated single electron tunneling in Co–Al–O and Cu–Al–O granular films using scanning tunneling microscopy (STM). Topographic images show well-defined granular structures where nanometer-sized metal granules are embedded in insulating matrix. The Coulomb staircases in the current–voltage (I–V) curves are clearly observed even at room temperature in both films. For the Co–Al–O film, furthermore, negative differential conductance appears in the Coulomb staircase. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 393-397 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Metallic multilayer films consisting of ferromagnetic PtMnSb and antiferromagnetic CuMnSb were prepared by an rf sputtering method. From the x-ray diffraction data, all the films were found to have a [111] texture of the C1b -type Heusler structure. The magnetization measured in PtMnSb/CuMnSb multilayers was larger than that in a PtMnSb compound. The temperature dependence of magnetization shows a bend at about 50 K near the Néel temperature of CuMnSb. This bend is explained qualitatively by using a molecular field model and assuming a trapezoidal modulation of exchange interaction.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 5586-5588 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: (Co0.5Fe0.5)BF amorphous films with modulated F content were investigated and such multilayered films have ceramic spacers to increase permeability at high frequencies. Modulated films having alternate F-poor layers (15 nm thick) and F-rich layers (5–10 nm thick) within an F content of 2–10 at. % were prepared by a sputtering technique. High-saturation induction (Bs) of 1.6–1.8 T, low coercivity (Hc) less than 1.0 Oe, permeability (μ') of 800–1000, and enhanced high frequency response were obtained in the case of a modulated film having alternating layers: 15-nm-thick layers, 2 at. % F, ρ=150 μΩ cm and 10-nm-thick layers, 10 at. % F, ρ=800 μΩ cm. The number of periods was variable. Auger-electron spectroscopy and secondary-ion mass spectroscopy depth profiles clarified the periodicity of the modulated films. Multilayered films with four layered F modulated films (0.55 μm/layer) and SiO2 spacers (0.24 μm/layer) exhibited an excellent frequency response of μ'=1500 in the range of 1–100 MHz. The coexistence of high ρ, high Bs, and low Hc in these films may be attributed to the oscillatory resistivity resulting from a compositional modulation in F and B.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: CoNbZr/ceramics multilayered films, the metal layers of which have sequentially changed anisotropy directions, were investigated. Such newly processed film is called "composite-anisotropy multilayer film.'' The effects of this new processing on soft magnetic properties were studied. In the case where the shift angle in the easy magnetization direction between neighboring CoNbZr layers is 45°, a smooth B-H loop with low coercivity was obtained. Furthermore, annealing from 200 to 400 °C resulted in high permeability (μ') of 1000–1500 and excellent frequency responses of μ' above 100 MHz in all directions in the plane of the film. These results could be explained in terms of magnetic interactions of the CoNbZr magnetic layers which are in close contact with one another across the intervening ceramics layers. These findings indicate that such composite film has many advantages over conventional uniaxial multilayers in applications to magnetic devices. Since these characteristics are thought to be very significant for microdevices composed of disc-shaped magnetic cores, we fabricated a planar microtransformer composed of circular spiral coils and disk-shaped magnetic cores, 2.4 mm in size, using photolithographic technology. The input–output voltage ratio, VOUT/VIN, was measured in the frequency range of 2–40 MHz and showed a high value of 0.83 at 40 MHz.
    Materialart: Digitale Medien
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