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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 5209-5214 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Grazing incidence x-ray reflectometry has been used to study surface oxidation as a diffusion barrier for Al deposited on ferromagnetic metals (Co, Fe, Ni, and Ni80Fe20). Samples of the form SiO2(backward-slash)10 nm X(backward-slash)4 nm Al with X=(Co, Fe, Ni, and Ni80Fe20) were investigated for X(backward-slash)Al intermixing. Surface oxidation was achieved by exposing the ferromagnetic layer to O2 to oxidize the top two or three atomic layers before depositing the Al layer. Specular x-ray scans were used for the analysis. Samples of the form SiO2(backward-slash)10 nm X(backward-slash)4 nm Au were used to separate topographical roughness from intermixing. Surface oxidation was found to suppress the diffusion of Al into Co, Ni, and Ni80Fe20 but not into Fe. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 3023-3026 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have studied the behavior of interlayer coupling in giant magnetoresistance spin valves as a function of seed layer composition and spacer layer thickness. Using in situ scanning tunneling microscopy, we have measured directly the roughness of the top surface of the lower ferromagnetic layer. We find that the seed layer composition is correlated to the roughnesses of the interfaces inside the spin valve. Interlayer coupling increases with decreasing Cu spacer layer thickness and with increasing interfacial roughness. Results favorably compare to a topographically derived magnetostatic interaction as described by a modified version of Néel's "orange peel" model. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 6825-6827 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has recently been found that large uniaxial anisotropy fields in excess of 120 kA/m (1500 Oe) can be created in thin (3–5 nm) films of Co by obliquely sputtered Ta underlayers. This anisotropy can be used to pin the bottom film of a spin valve while having only a modest effect on the top "free" film, separated by a 2.5 nm Cu spacer layer. This article describes measurements of thermal stability in these Ta-pinned spin valves. Using room temperature giant magnetoresistance (GMR) as a measure, we find that the structure is stable under cumulative 20 min anneals at 25 °C intervals up to 300 °C; GMR decreases to zero upon further anneals up to 450 °C. Measurements taken at elevated temperatures reveal that GMR decreases linearly with temperature, extrapolating to zero at approximately 425 °C, while the anisotropy field is much less temperature dependent, remaining nearly constant up to 150 °C and gradually decreasing to 50% of its room temperature value at 325 °C. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 6406-6408 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Because the memory of the bias direction is carried by the antiferromagnetic order in exchange biased films, the stability of the antiferromagnetic order is critical to the existence of the exchange bias field. Ferromagnetic resonance was used to measure the relaxation behavior of polycrystalline CoO films coupled to films of Ni80Fe20, probing the system on the time scale of the experiment, (approximate)103 s, and the time scale of the magnetic precession, (approximate)10−10 s. Unidirectional anisotropy (exchange biasing) and isotropic resonance field shifts are observed at the lowest temperatures. Above the apparent exchange bias blocking temperature, isotropic resonance field shifts persist. At still higher temperatures, diminishing resonance field shifts are accompanied by peaks in the FMR linewidth. The results highlight the effects of varying relaxation rates in the CoO relative to the two experimental time scales. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 2 (1983), S. 1145-1155 
    ISSN: 0392-6737
    Keywords: Acoustical properties of solids ; Ultrasonics, quantum acoustics and physical effects of sound ; Transduction, devices for the generation and reproduction of sound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Un sistema interferometrico laser a spostamento è stato adattato per misurare gli spostamenti meccanici di campioni di materiali piezoelettrici e ferroelettrici trascinati da campi elettrici ciclici. Si trova che possono esistere risonanze meccaniche di ampiezza abbastanza grande indipendentemente da qualsiasi apprezzabile disturbo elettrico. Le si riscontra anche in campioni vergini e depolarizzati di ceramiche ferroelettriche. Le prime prove sperimentali suggeriscono che questo fenomeno dipende nella struttura a domìni dei materiali ferroelettrici.
    Abstract: Резюме Смещние лазерной интерферометрической системьи бьило приспособ-пено для измерения меанических смещений образцов пяезоэлектрических и ферроэлектрических материалов, вьизванньих циклическими электрическими полями. Обнаружено, что мэханические резонансьо с довольно большми амплитудами могут существоать независимо для любьих заметньих электрических возмушений. Эти резонансьи также обнаруженьи в образцах феррозлектрической кереники. Предварительньие экспериментальньие результатьи свипетельствуют, что это явление зависит от домэмами струкурьи ферроэлектричэскик матэроалпв.
    Notes: Summary A displacement laser interferometer system has been adapted to measure the mechanical displacements of specimens of piezoelectric and ferroelectric materials driven by cyclic electric fields. It is found that mechanical resonances of quite large amplitudes can exist independent of any noticeable electrical disturbances. They are also detected in virgin and depoled specimens of ferroelectric ceramics. Preliminary experimental evidence suggests that this phenomenon depends on the domain structure of the ferroelectric materials.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 4 (1984), S. 280-292 
    ISSN: 0392-6737
    Keywords: Anelasticity ; internal friction ; and mechanical resonances
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Un nuovo fenomeno di accoppiamento elettromeccanico è stato determinato nella ceramica elettroottica PLZT 7/65/35 con l’aiuto di un sistema interferometro-laser a raggio doppio. Specificamente, quando si applica un voltaggio d.c. a piccola ampiezza attraverso un campione vergine di materiale, il campione deflette nella direzione opposta alla direzione positiva del voltaggio con nessuno sforzo assiale misurato associato. L’osservazione resta valida quando è innescata la polarità del voltaggio. Quando si applicano voltaggi a.c., i comportamenti vibrazionali e il senso degli spostamenti meccanici dipendono dagli intervalli di frequenza dei voltaggi applicati. In particolare, essi cambiano quando il campione passa attraverso quelle specifiche risonanze meccanichesolo con anelli nodali e non attraverso quelle con anelli nodalie diametri nodali.
    Abstract: Резюме Обнаружено новое явление электромеханической связи в злектрооптической керамике PLZT 7/65/35 с помощью двухлучевой лазерной интерферомет-рической системы. Когда небольшое постоянное напряжение подается на исходный образец материала, то образец будет изгибаться в направлении противоположном положительному направлению напряжения, что сопровождается неизмеримым аксиальным напряжением. Явление по-прежнему имеет место, если полярность приложенного напряжения изменяется. Когда прикладывается переменное напряжение, то колебания образца и направление механических смещений зависят от области частот приложенных напряжений. В частности, они изменяются, когда образец проходит через определнные механические резонансы.
    Notes: Summary A new electromechanical-coupling phenomenon has been detected in the electro-optic ceramic PLZT7/65/35 with the aid of a dual-beam laser-interferometer system. Specifically, when a low-amplitude d.c. voltage is applied across a virgin specimen of the material, the specimen will deflect in the direction opposite to the positive direction of the voltage with no measurable accompanying axial strain. The observation remains valid when the polarity of the voltage is switched. When a.c. voltages are applied, the vibrational patterns and the sense of the mechanical displacements depend on the frequency ranges of the applied voltages. In particular, they change when the specimen goes through those specific mechanical resonances with nodal ringsonly, and not those with nodal ringsand nodal diameters.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 38 (1981), S. 209-218 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Die mechanischen, piezoelektrischen und dielektrischen Eigenschaften ferroelektrischer Keramiken können ziemlich kompliziert sein. Diese Materialien zeigen sowohl instantane als auch vorübergehende Antworten, die von verschiedenen physikalischen Mechanismen wie Dipoldynamik und Bereichsumschaltung abhängen. Daher sind die Werkstoffgleichungen für die Spannung und die elektrische Verschiebung, die formuliert wurden, recht kompliziert und ihre Beschreibung kann ziemlich verwickelt sein. Diese Werkstoffgleichungen müssen auch die Gleichgewichtsantworten der Keramiken beschreiben, wenn vorübergehende Prozesse zum Stillstand kommen. In dieser Arbeit zeigen wir, daß bei kenntnis der Schallgeschwindigkeiten einer ursprüglichen und einer gepolten Abart einer ferroelektrischen Keramik und bestimmter, damit verbundener Eigenschaften der Hysterese und Schmetterlingsschleifen eine Beschreibung ihrer Gleichgewichtsmaterialeigenschaften in der polaren Richtung im Einklang mit einer expliziten Version der Werkstoffgleichungen für die Spannung und die elektrische Verschiebung möglich ist.
    Notes: Summary The mechanical, piezoelectric and dielectric properties of ferroelectric ceramics can be quite complicated. These materials exhibit both instantaneous and transient responses depending on various physical mechanisms such as dipole dynamics and domain switching. Hence the constitutive relations for the stress and the electric displacement which have been formulated are quite complicated and their characterization can be rather intricate. These constitutive relations must also describe the equilibrium responses of the ceramics when the transient processes have come to rest. In the paper, we show that knowledge of the sound speeds of a virgin and a poled specimen of a ferroelectric ceramic and certain associated properties of the hysteresis and butterfly loops permits the characterization of its equilibrium material properties in the polar direction consistent with an explicit version of the constitutive relations for the stress and the electric displacement.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 41 (1981), S. 255-264 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Description / Table of Contents: Zusammenfassung Die Werkstoffgleichungen und Geschwindigkeitsgesetze wie von Chen und Peercy in [1] vorgestellt, wurden erfolgreich zur Beschreibung der eindimensionalen, polaren mechanischen und dielektrischen Reaktionen der elektrooptischen Keramik PLZT 7/65/35 in einem langsam veränderlichen, zyklischen elektrischen Feld eingesetzt. Insbesondere wurden die Wirkungen der Bereichsumschaltung untersucht und die mit den Schmetterlings- und Hystereseschliefen verbundenen Ergebnisse berechnet. Die Übereinstimmung zwischen den numerischen und den experimentellen Ergebnissen ist zufriedenstellend.
    Notes: Summary The constitutive relations and rate laws proposed by Chen and Peercy [1] have been successfully implemented in describing the one dimensional polar mechanical and dielectric responses of the electrooptic ceramic PLZT 7/65/35 to a slowly varying cyclic electric field. In particular, we examine the consequences of domain switching and determine the results associated with the butterfly and hysteresis loops. The agreement between the numerical and the experimental results is quite good.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 51 (1984), S. 217-226 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In this paper, we examine certain characteristics of two electrically excitable mechanical resonances exhibited by two different specimens of the ferroelectric ceramic PZT 65/35. In particular, we determine the phase angle between the charge and the driving voltage, the current in the circuit, the amplitude of the mechanical displacement, and the electrical power dissipated in driving the specimens at each of these resonances for increasing amplitude of the driving voltage. It is shown that the phase angle, the current and the power dissipated have similar characteristics for the two resonances; but their mechanical displacements have entirely disparate features. In one case the amplitude increases more than linearly with respect to the driving voltage, whereas the contrary is true in the other case.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Acta mechanica 47 (1983), S. 95-106 
    ISSN: 1619-6937
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary In this paper we characterize the isothermal three dimensional properties of a poled ferroelectric ceramic PZT 65/35 in the absence of losses. The resulting constitutive relations, in the absence of mechanical dissipation, domain switching, dipole dynamics and phase transformation, are the standard ones which appear in the literature. The characterization of the constitutive relations requires the determination of five elastic constants, three piezoelectric constants and two dielectric constants. We dientify the experimental measurements which are sufficient to determine these constants and describe the data reduction procedures. Our results differ relatively and absolutely from those given in the literature.
    Type of Medium: Electronic Resource
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