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  • 1
    Electronic Resource
    Electronic Resource
    Direct measurement of spin dependent mean free paths in metals (abstract) : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 7079-7079 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe results obtained using a new spin valve structure that is specifically designed to measure the spin up and spin down mean free paths in ferromagnetic metals. We report how these mean free paths can be measured more directly and with greater accuracy than previous methods, which were based mostly on indirect evidence from magnetoresistance in ternary alloys. The technique is based on the "backed'' spin valve layered structure: substrate/seed/80 A(ring) FeMn/50 A(ring) NiFe/23 A(ring) Cu/20 A(ring) NiFe/t A(ring) b/50 A(ring) Ta where the back layer of material b with thickness t is probed by the rest of the structure, which forms a spin polarized conduction electron source. As t is varied the majority carrier mean free path λ+b in the layer b is obtained directly from the form taken by the change in film conductance between parallel and antiparallel magnetization states, ΔG, whose solution of the Boltzmann transport equation shows is well approximated by the form ΔG=ΔG0+ΔGb{1−exp([t−tx]/βλ+b)}, where ΔG0 arises from the 20 A(ring) NiFe layer, tx is the high resistivity region of intermixing at the b layer interfaces, and β(approximately-equal-to)1 from observations with b=Cu. The minority carrier mean free path in a ferromagnetic layer b, λb, is obtained by comparing ΔG and λ+b with ΔG', and λb'+, of a nonmagnetic b' layer of similar resistivity to b; it is a less direct measurement than that of λ+ since it relies on the connection between conductivity and mean free path for the minority subband. We have obtained room temperature results for Ni80Fe20 (λ+=46±3 A(ring), 0〈λ〈6 A(ring)), Fe (λ+=15±2 A(ring), λ=21±5 A(ring)), and Co (λ+=55±4 A(ring), 0〈λ〈8 A(ring)). The connection of spin dependent conductivity and mean free paths in ferromagnetic metals is crucial in exploring the mechanism of giant magnetoresistance and, more broadly, is central in all theories of transport in magnetic metals; this new technique should prove a powerful tool in measuring these fundamental quantities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.356733
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  • 2
    Electronic Resource
    Electronic Resource
    Parameters, affecting the sensitivity of poly(methyl methacrylate) as a positive lithographic resistA detailed paper on this subject will appear in the IBM J. Res. Dev., 21, (2)(1977) (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 396-401 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The contribution of parameters such as molecular weight, molecular weight distribution and stereochemistry to electron beam sensitivity of poly(methyl methacrylate), PMMA, has been investigated. The sensitivity is interpreted here as the minimum radiation dose required to obtain a predetermined solubility rate ratio, S/So = SR, of the exposed, S, and unexposed, So, material. The G-value was foam be independent of molecular weight, molecular weight distribution, and stereochemistry. Data indicate that the weight average molecular weight ratio correlates better with SR than the number average molecular weight ratio. The tacticity of the resist and the developer solvent molecular weight or size have a large effect on solubility rate. Although the solubility rate pf isotactic PMMA is much greater than the syndiotactic and heterotactic stereoforms, the sensitivity appears to be independent of tacticity. In a homologous series of n-alkyl acetate developer solvents, the molecular size of the solvent has a greater effect on the solubility rate than the molecular weight of the resist. A developer solvent has been selected from the n-alkyl acetates which enhanced the sensitivity of PMMA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170613
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  • 3
    Electronic Resource
    Electronic Resource
    The synthesis and evaluation of cyclic olefin sulfone copolymers and terpolymers as electron beam resists (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 677-688 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(cyclopentene sulfone) (PCPS) and poly(bicycloheptene sulfone) (PBCHS) copolymers have been evaluated as potential positive electron beam resists which have good thermal properties and which show high sensitivity to ionizing radiation. It was found that thin copolymer films could be processed as resists but that films greater than 3000 Å thick cracked in the solvents used to dissolve the radiation-exposed regions. Incorporation of plasticizing additives did not improve the film properties. Films from low molecular weight polymer fractions cracked less in solvents, but higher radiation doses were required to offset the reduced sensitivity. This resulted in the formation of intractable residues in the exposed regions which appear to be crosslinked polymer. Bicycloheptene monomers with specific functional groups did not improve the properties of the copolymer films. Terpolymerization with α-olefins such as butene-1 and cis-2-butene plasticized these films and reduced their tendency to crack in solvents. Poly(cyclopentene sulfone-co-butene-1 sulfone) films were found to have the best properties, and 1.25-μ resist images could be etched in SiO2 layers at an exposure dose of 4 × 10-6 C/cm2 at 25KV. However, one important limitation of this terpolymer was the low dissolution rate ratio between the exposed and unexposed regions. Since straight-walled relief images are essential to the formation of high-resolution patterns, the usefulness of this terpolymer as an electron beam resist appears to be hindered by the limited choice of good solvents to maximize the dissolution rate ratio. PBCHS block terpolymers containing methyl methacrylate (MMA) or methacrylic acid (MAA) were synthesized to improve the solubility in solvents and to incorporate the properties of methacrylates. PBCHS-MMA films cracked in solvents after irradiation; PBCHS-MAA polymers were too insoluble to form resist films.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210309
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis of vinylfluorene-vinylfluorenone polymers (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Letters 9 (1971), S. 671-676 
    Details
    ISSN: 0449-2986
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.110090907
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of 5-vinyl-2,2′-bithiophene (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 813-816 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090321
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of homologous monomers and polymers of carbazole, phenothiazine and dibenzazepine (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 3285-3294 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monomers and polymers of 3-vinyl-N-ethylcarbazole, 3-vinyl-N-methylphenothiazine, 3,7-divinyl-N-methylphenothiazine, N-acrylylcarbazole, N-acrylylphenothiazine, and N-acrylyl- and N-methacrylyldibenzazepine have been synthesized. The synthetic procedures for preparing the monomers and polymers are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.150081121
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesis and polymerization of 5-vinyl-2,2′-bithiophene (1971)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 1785-1785 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1971.150090633
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