bluuebunny/crossref_metadata_2025_split huggingface dataset:
Über die Ummagnetisierung dünner ferromagnetischer Schichten mittels zweisinniger Drehung
Authors: Vinogradov O. A. 
Published: July 2007

AbstractIn der vorliegenden Arbeit wird der Ummagnetisierungsprozeß einer dünnen ferromagnetischen Schicht durch zweisinnige Drehung auf der Grundlage folgenden Modells berechnet: Gebiete mit wechselnder Drehrichtung bilden Bänder gleicher Breite, die senkrecht zur ursprünglichen Magnetisierungsrichtung liegen. Auf der Basis dieses Modells werden notwendige Bedingungen für die Ummagnegtisierung der Schicht infolge zweisinniger Drehung erhalten. Es erweist sich als entscheidend, daß sich die Grenzen zwischen Gebieten unterschiedlicher Drehrichtung im Verlauf der Ummagnetisierung in ständiger Bewegung befinden. Nur für sehr dünne Schichten (mit einer Dicke kleiner als 100 Å für Permalloy) bleiben diese Grenzen unbeweglich, und die Zweisinnigkeit der Drehung hat fast keinen Einfluß auf die Ummagnetisierungsgeschwindigkeit.
Nuclear Polarization by Hot Carrier Flow in Semiconductors
Authors: Kalashnikov V. P. 
Published: July 2007

AbstractThe nuclear polarization resulting from the interaction of the nuclei with a non‐equilibrium, steady‐state, distribution of hot conduction electrons generated by crossed static magnetic and strong electric fields is investigated theoretically. The effect of a strong electric field on the spin‐lattice relaxation times of the conduction electrons and the relaxation time of the nuclei by hyperfine interaction with hot carriers are considered for various types of semiconductors. Formulae for the field‐enhanced nuclear magnetization, and for the relaxation times of the electronic and nuclear magnetic moments, are obtained as functions of the current density of the conduction electrons.
Elastic and Core Anisotropies for the 〈111〉 Screw Dislocation in Cubic Crystals
Authors: Hirth J. P. , Lothe J. 
Published: July 2007

AbstractThe stress component s̀rz which gives rise to an angular force between parallel screw dislocations is calculated. The stress components tend to stabilize a pile‐up of screws on a {112} plane, while they would add to the instability of pile‐ups on {110} planes. Sodium is an extreme case in which a pile‐up on {112} should be elastically stable so that it cannot disperse by cross‐slip. It is also demonstrated that in general there are asymmetries in the dislocation cores, which are manifested as important asymmetries in dislocation mobility and cross‐slip processes.
On the Electrical Properties of Some Iron‐Copper and Copper‐Manganese Ferrites
Authors: Rosenberg M. , Nicolau P. , Bunget I. 
Published: July 2007

AbstractThe electrical conductivity and Seebeck coefficient of some iron‐copper and copper‐manganese ferrites are investigated. The electrical properties are found to be highly dependent on the preparation conditions and this is explained by the chemical reduction of the Cu2+ ions above 900 °C. For the iron‐copper ferrites a mixed conduction mechanism is proposed. The n‐carriers are electrons on Fe3+ levels and these are dominant in the slowly cooled samples. The p‐carriers are holes on oxygen ions, these being dominant in samples quenched from temperatures above 1120 °C. An irreversible increase of the Seebeck coefficient and resistivity is produced by heating the quenched samples in the temperature range 350 to 550 °C, and this is due to oxidation of the Cu1+ ions.
The Effect of Orientation on the Yielding and Flow of Molybdenum Single Crystals
Authors: Guiu F. , Pratt P. L. 
Published: July 2007

AbstractThe influence of the orientation with respect to the direction of stresses has been investigated over the temperature range 77 to 413 °K. At temperatures below 300 °K the limit of the proportionality of strain to stress and the rate of work‐hardening depend markedly on the orientation. At temperatures above 300 °K the yield stress is practically independent of the orientation and the crystals can experience a large elongation without necking. Crystals with the tensile axis orientated in a direction near the centre of the unit stereographic triangle exhibit three work‐hardening stages. Slip lines and etch pit observations have shown that profuse cross‐slip of screw dislocations is a characteristic feature of the deformation of molybdenum single crystals. An explanation, based on the mobility of the jogs in screw dislocations, is proposed for the orientation dependence of the yield stress.
Contribution à I'analyse du frottement interne dépendant de I'amplitude de déformation
Authors: Peguin P. , Perez J. , Gobin P. 
Published: July 2007

AbstractLa mise en évidence nette du frottement interne du type ΔH du au dépiégeage thermomécanique des lignes de dislocations exige qu'on l'isole du frottement interne lié à la déformation plastique ΔP. Nous montrons qu'un léger écrouissage appliqué à un alliage aluminium‐zinc à zinc répond à cette exigence. Par ailleurs, nous proposons une relation décrivant ΔP.
Raumladungsbegrenzte Elektronendunkelströme in KCl
Authors: Tödheide‐Haupt U. , Gysler A. , Ruppel W. 
Published: July 2007

AbstractIn zonengereinigten und nicht‐zonengereinigten KCl‐Kristallen der Dicke zwischen 6 und 1000 μm nehmen bei 20 und 100°C für hinreichend kleinen Elektrodenabstand L die gemessenen Stromdichten j proportional L−3 zu, während für dickere Kristalle, der Ionenleitung entsprechend, j ∼ L−1 gefunden wird. Eine Interpretation der L−3‐proportionalen Ströme in zonengereinigten Kristallen als raumladungsbegrenzte Elektronenströme führt unter der Annahme eines diskreten Haftstellenniveaus zu einer Haftstellenkonzentration der Größenordnung der Konzentration der Gitterionen, was auf self‐trapping der injizierten Ladungsträger schließen läßt. Für die in nicht‐zonengereinigten Kristallen bei 100°C beobachteten L−3‐proportionalen Ströme wird auf Grund ihrer mit der der Ionenleitung übereinstimmenden Temperaturabhängigkeit die Deutung als raumladungsbegrenzte Ionenströme vorgeschlagen.
Propagation des macles dans les métaux fortement écrouis
Authors: Fontaine G. 
Published: July 2007

AbstractOn étudie d'un point de vue théorique le développement d'une lamelle de macle mécanique à travers le réseau de Frank d'un métal cubique à faces centrées fortement écroui. On prévoit l'existence sur les joints de macle de dislocations de macle joignant les arbres à caractère vis qui percent ces joints. Ces dislocations sont d'autant plus longues et rapprochées qu'elles se trouvent plus proches des extrémités de la macle où elles constituent alors de véritables empilements. On étudie le frottement qu'il faut surmonter pour produire l'épaississement des lamelles maclées. On montre qu'il est essentiellement dû à la nécessité de faire fonctionner en sources de Frank et Read les segments de dislocations de macle au centre des joints. On montre que les autres termes dans le frottement dû au réseau sont négligeables. On généralise enfin l'analyse à d'autres structures (hexagonaux et cubiques centrés).
On the Analysis of Experimental Data on Point Defect Recovery
Authors: Gevers R. , Nihoul J. , Stals L. 
Published: July 2007

AbstractA general method is derived for transforming isothermal annealing equations into expressions for the recovery as a result of arbitrary thermal treatment. Three types of treatment are considered in detail: linear continuous heating, linear isochronal pulse heating and hyperbolic isochronal pulse heating. The latter is shown to present some real advantages since in this case the transformation can be made without approximation. It is shown that linear isochronal pulse annealing data may be treated in good approximation by using the expression for continuous linear heating, if a rather severe condition is fulfilled (ΔT ⪅ (k T + 2o/E) and provided that the annealing temperature Tp is replaced by Tp + 1/2 ΔT. By this method the isothermal annealing equations, as derived by Waite for the case of bimolecular diffusion‐controlled reactions between homogeneously‐distributed defects, are adapted for application to isochronal annealing data.
Analytical Study of Isochronal Annealing of Cold‐Worked Niobium
Authors: Stals L. , Nihoul J. , Gevers R. 
Published: July 2007

AbstractThe theoretical expressions derived in the preceding paper are applied to stage III isochronal annealing data for cold‐worked niobium. Close agreement between the experimental data and the theory is obtained by using the model based on uncorrelated bimolecular recombination of defects. This confirms an earlier proposed mechanism for stage III recovery in b.c.c. metals, namely recombination of randomly migrating interstitials with immobile vacancies.
Quantum Oscillations of Transport Coefficients in n‐Type Indium Arsenide
Authors: Bresler M. S. , Redko N. A. , Shalyt S. S. 
Published: July 2007

AbstractOscillations in the magnetoresistance, Hall coefficient, and thermoelectric power in transverse and longitudinal strong magnetic fields are studied for different polycrystalline samples of n‐InAs at liquid helium temperatures. Some pecularities, which have also been observed previously in n‐InSb, cannot be explained by existing theory and need special theoretical treatment.
Magneto‐Phonon Oscillations of the Light Absorption Coefficient in the Intrinsic Absorption Region
Authors: Korovin L. I. 
Published: July 2007

AbstractA theory is developed for the line‐shape of the Interband oscillatory magneto‐optical absorption coefficient. The non‐stationary character of the electron states is assumed to originate from inelastic interactions between electrons and optical (polar) phonons. It is shown that the width and shift of electron levels depends non‐monotonically on the magnitude of the magnetic field, which leads to additional oscillations of the absorption coefficient which are of the magneto‐phonon resonance type. Theoretical estimates indicate that these additional oscillations should be experimentally observable.
Mößbauer‐Untersuchungen an Mn‐ und MgMn‐Ferriten
Authors: Wieser E. , Meisel W. , Kleinstück K. 
Published: July 2007

AbstractDie Mößbauer‐Spektren von stöchiometrischem Mn‐Ferrit sowie zwei MgMn‐Ferriten wurden bei Zimmertemperatur und bei der Temperatur des flüssigen Stickstoffs aufgenommen. Bei Zimmertemperatur wurde eine Überlagerung zweier Sechs‐Linien‐Spektren unterschiedlicher Intensität für alle drei Proben gefunden, die sich in den Tieftemperaturspektren nicht mehr nachweisen läßt. Die zwei überlagerten Spektren werden den Fe3+‐Ionen auf Tetraeder‐ und Oktaederplätzen zugeordnet. Für die beiden MgMn‐Ferrite ergibt sich dabei, daß das größere Magnetfeld am Kernort dem Untergitter mit dem kleineren mittleren magnetischen Moment entspricht. Zur Erklärung dieses Sachverhaltes werden Abweichungen von der kollinearen Néelschen Spinkonfiguration auf Oktaederplätzen diskutiert.
Delayed Fluorescence and Thermoluminescence of Anthracene Single Crystals at Very Low Temperatures
Authors: Riehl N. , Thoma P. 
Published: July 2007

AbstractThe delayed fluorescence of anthracene single crystals of various origins is measured at 77 and 4.2 °K. At 4.2 °K the decay time of the delayed fluorescence is much larger than at 77 °K. The optical glow curves of the crystals are measured in the temperature range 4.2 to 77 °K after excitation with UV light. The nature of the traps responsible for the glow peaks is discussed.
Pumping Induced Imperfections in Glass:Nd3+ Lasers
Authors: van Torne L. I. 
Published: July 2007

AbstractA barium crown glass:Nd3+ laser rod which developed permanent internal imperfections during laser pumping was investigated by optical metallography, transmission electron microscopy, and electron diffraction techniques. The imperfections were found to be microcracks resulting from differential thermal expansion between crystallites (resulting from devitrification) and the surrounding noncrystalline medium. An analysis of the kinetics of devitrification, the radial temperature distribution during pumping and stresses resulting from differential thermal expansion are in agreement with a proposed mechanism for the development of permanent internal imperfections.
On the Velocity of Space Charge Waves (Electrical Domains) in Semiconductors
Authors: Kalashnikov S. G. , Bonch‐Bruevich V. L. 
Published: July 2007

AbstractThe non‐linear problem of the velocity of space charge waves (electrical domains) which occur when the volume differential resistance becomes negative is studied. Particular attention is paid to the recombination (concentration controlled) type of instability. The domain velocity is derived for the cases in which the Maxwellian relaxation time is much greater or much smaller than the recombination time. The results obtained are in order of magnitude agreement with experimental data on domains in Au‐ and Cu‐doped Ge [13, 15].
Rectifying and Photoconductive Properties of p‐GaSe Single Crystals
Authors: Abdullaev G. B. , Akhundov M. R. , Akhundov G. A. 
Published: July 2007

AbstractThe current‐voltage characteristics of a CdGaSeBi diode structure are given for different values of temperature and illumination. The photovoltage and photocurrent characteristics and the photocurrent spectral distribution are also presented. The mean rectification coefficient is 104 at U = 2 V. The activation energies obtained from the temperature dependence of the exponential part of the forward current characteristic for different samples are grouped around the values 0.60 and 0.34 eV. The values of the open circuit voltage (V oc) and of the short circuit current (Isc) lie between 250 to 450 mV and 300 to 900 μA/cm2 respectively. It is found that photocells based on GaSe have a better time‐response than GaSe photoresistors.
Magnetostriktiver und magnetokristalliner elektrischer Restwiderstand in Ferromagnetika
Authors: Kronmüller H. , Seeger A. 
Published: July 2007

AbstractIm Rahmen der Bornschen Näherung wird in einem einfachen Modell die Streuung von s‐Elektronen in ferromagnetischen Metallen an räumlich inhomogenen Spinverteilungen der d‐Elektronen behandelt. Als maßgebend für die Streuung der s‐Elektronen wird die sd‐Austauschkopplung betrachtet. Die allgemeine Theorie wird zur Berechnung des elektrischen Restwiderstandes der Versetzungen infolge magnetischer Inhomogenitäten herangezogen. Der magnetostriktive Restwiderstand einer Versetzung verschwindet wie 1H2 mit wachsender äußerer Feldstärke. Bei kleinen Feldstärken nähert sich der Restwiderstand einem konstanten Wert. Bei plausiblen Annahmen über die Stärke der sd‐Austauschkopplung ergibt sich der magnetostriktive Restwiderstand als hinreichend groß, um experimentell nachgewiesen werden zu können.
Zur Bestimmung der freien Weglänge der Elektronen aus Messungen der Ultraschallabsorption in Metallen
Authors: Mertsching J. 
Published: July 2007

AbstractEs werden verschiedene Methoden zur Bestimmung der freien Weglänge der Elektronen in Metallen eingehend diskutiert, die auf Messungen der longitudinalen Ultraschallabsorption im äußeren Magnetfeld beruhen. Es handelt sich dabei um die Bestimmung der Anzahl geometrischer Resonanzen und der Dämpfung ihrer Amplituden sowie um die Änderung der Absorption beim Einschalten eines hohen Magnetfeldes. Es wird gezeigt, daß die gebräuchliche Auswertung der Messungen der geometrischen Resonanz inkorrekt ist und viel zu große freie Weglängen ergibt. Dadurch werden die bestehenden Diskrepanzen zu den Ergebnissen der Messungen im hohen Magnetfeld erheblich verringert. Die restlichen Diskrepanzen weisen auf Abweichungen realer Metalle vom Modell freier Elektronen hin, auf dessen Grundlage die Messungen im hohen Magnetfeld ausgewertet wurden.
Étude et interprétation du stade I dans le nickel irradié aux électrons à 20°K
Authors: Peretto P. , Oddou J. L. , Minier‐Cassayre C. , Dautreppe D. , Moser P. 
Published: July 2007

AbstractDes expériences couplées de traînage magnétique et de restauration de la résistivité électrique sur du Nickel pur et dopé de fer, irradié aux électrons à 20°K, permettent de proposer un modèle détaillé de la structure des défauts ponctuels évoluant au cours du stade I. Chaque sous‐stade est attribué à l'annihilation d'annihilation d'interstitiels placés sur des groupes de sites équivalents par rapport à la lacune sur lesquels ils peuvent éventuellement migrer avant da disparaître.
A New Property of Ferromagnetic‐Antiferromagnetic Coupling
Authors: Paccard D. , Schlenker C. , Massenet O. , Montmory R. , Yelon A. 
Published: July 2007

AbstractThree systems exhibiting ferromagnetic‐antiferromagnetic coupling, CoCoO, NiFeNiFeMn, NiFeCr2O3, are studied using uniaxial thin films. A new property of such systems is found, i.e., a concentration of the hysteresis loops as a function of the number of cycles traced (n). This contraction follows a 1/\documentclass{article}\pagestyle{empty}\begin{document}$\sqrt n $\end{document}n law for the first 50 cycles and is related to the rotational hysteresis. This phenomenon is attributed to fluctuations in the ferromagnetic‐antiferromagnetic coupling, which modify the magnetic interactions between differently coupled regions with each reversal.
On the Theory of the Superexchange Interaction in Ionic Crystals: KNiF3
Authors: Šroubek Z. 
Published: July 2007

AbstractStudies are made of superexchange interaction in ionic crystals using the Heitler‐London theory and with particular reference to KNiF3. The generalized Heitler‐London quantitative theory of covalency allows a detailed study to be made of the transfer of an electron from cation to cation and the transfer of two electrons from an anion to the cations. No further assumptions are made and the calculations are performed numerically. The antiferromagnetic superexchange constant given by this calculations is in good agreement with the experimental superexchange constant.
Determination of Diffusion Coefficients in Metals by a Resistometric Method ‐ Application to the Diffusion of Zn in Al
Authors: Ceresara S. , Federighi T. , Pieragostini F. 
Published: July 2007

AbstractA method is described for determining the diffusion coefficient in dilute solid solutions by measurements of the electrical resistivity. The diffusion equation is solved numerically for the selected experimental conditions and this provides curves suitable for direct comparison with experimental data. Results obtained for the diffusion parameters of Zn in pure Al indicate the accuracy of the method.
Magnetic and Structural Characteristics of Some Equiatomic Rare‐Earth Germanides
Authors: Buschow K. H. J. , Fast J. F. 
Published: July 2007

AbstractMagnetic and structural data are given for eleven rare‐earth germanium intermetallic compounds represented by the formula RGe. The FeB type of structure is observed for R = La and Ce, while the CrB type is found for R = Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Y. The compounds LaGe and YGe are Pauli paramagnets. The compounds PrGe and NdGe are found to become ferromagnetically ordered upon cooling, whereas the compounds CeGe, SmGe, GdGe, TbGe, DyGe, and ErGe order antiferromagnetically. A field‐induced transition from the antiferromagnetic state to a ferrimagnetic state is observed for the compound HoGe at 4.2°K when studied in moderate fields; when pulsed field up to 80.000 Oe is used a second transition point is observed. The susceptibility at high temperatures of most of the compounds follows the Curie‐Weiss law with effective moments close to those of the trivalent free rare earth ions. In the case of SmGe, a contribution to the susceptibility from higher multiplets is observed.
Untersuchungen über Ummagnetisierungsprozesse in Rechteckferriten
Authors: Steinbeiss E. 
Published: July 2007

AbstractEs wurde der Einfluß einer einachsigen Anisotropieenergie auf die Feldstärkeabhängigkeit der Ummagnetisierungszeit untersucht und die Ergebnisse im Zusammenhang mit einigen Modellvorstellungen über Ummagnetisierungsprozesse diskutiert.
Electron Diffraction Contrast of Small Stacking Fault Tetrahedra with Applications to Quenched Gold
Authors: Chik K.‐P. 
Published: July 2007

AbstractIt is shown that the characteristic diffraction contrast of small stacking fault tetrahedra obtained by imaging with a {220} reflection can be used to distinguish small unresolved stacking fault tetrahedra from dislocation loops. Application of these results to quenched gold shows that vacancy clusters exist already in their early stage as stacking fault tetrahedra.
On the Strengthening Mechanism in Neutron Irradiated Copper Single Crystals. I. On Experiments Concerning Strain Rate Changes Critical Comments on the Preceding Paper of T. J. Koppenaal and R. J. Arsenault
Authors: Schwink Ch. , Neuhäuser H. 
Published: July 2007

AbstractStrain rate changes are used for analysing the flow stress of n‐irradiated copper crystals and lead to the following conclusions: a) The “active crystal length”, i. e. the number of simultaneously active slip planes, increases with the strain rate \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma $\end{document}, resulting in \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma $\end{document} not being proportional to ⋖ (cross‐head speed) [1]. b) The critical shear stress (css) varies with ⋖ more rapidly than is expected from theory [2]. In the preceding paper [3] arguments are advanced against both of these statements. All of these arguments will be invalidated. The proportionality \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma $\end{document} ∼ ⋖ is shown to represent a rather special case from an atomic point of view. By far more general is a non‐proportionality \documentclass{article}\pagestyle{empty}\begin{document}$\dot \gamma $\end{document} ≁ ⋖. Taking this into accont one succeeds in describing straightforwardly the results of b). New experiments supporting our former statements are going to be reported. All conclusions drawn previously [4, 5, 6] on the strengthening mechanism in copper and based on a) and b) can be fully maintained [7].
The Raman Spectrum of NaNO2 in the Ferroelectric Phase
Authors: Chisler E. V. , Shur M. S. 
Published: July 2007

AbstractThe Raman spectrum of a NaNO2 single crystal in the ferroelectric phase is obtained and the polarization of the lines is investigated. The forms of normal vibrations are considered on the basis of symmetry coordinates and the intensity of lines. Formulae for translational vibrations are derived and numerical calculations are performed taking into account shortrange repulsive forces between nearest neighbours and long‐range Coulomb forces.
Optical and Thermal Properties of Color Centers in CsBr Single Crystals Irradiated at Liquid‐Helium Temperature
Authors: van de Wiele F. , Jacobs G. 
Published: July 2007

AbstractAbsorption bands at 435 and 437 nm, induced in CsBr single crystals by X‐irradiation at liquid‐helium temperature, are interpreted as being due to H centers. Underlying bands are observed in the region of the F absorption band. Optical and thermal interactions between the F and V type and α bands are shown to be present and mechanisms for these interactions are proposed. The formation of a new absorption band at 320 nm during the thermal bleaching is observed. Some optical and thermal properties of this band are examined.
Raumladungsbegrenzte Ströme in inhomogen belichteten CdS‐Einkristallen
Authors: Fischer R. , Stöckmann F. , Stuke J. 
Published: July 2007

AbstractRaumladungsbegrenzte Ströme wurden an photoleitenden CdS‐Kristallen untersucht, bei denen ein schmaler Streifen zwischen den Elektroden schwächer belichtet wurde als der übrige Kristall. Bei diesen inhomogen belichteten Kristallen wird der Strom in dem schwach belichteten Streifen bereits bei kleinen Spannungen durch Raumladungen begrenzt, wobei das angrenzende stärker belichtete Gebiet auf der Seite der Kathode als injizierender Kontakt wirkt. In dieser Anordnung war es möglich, alle für raumladungsbegrenzte Ströme charakteristischen Abhängigkeiten von der Spannung, dem Elektrodenabstand und der Dunkelkonzentration der Ladungsträger an ein und derselben Probe zu messen. Alle Meßergebnisse stimmen gut mit den Gesetzmäßigkeiten überein, die für Kristalle mit flachen Elektronen‐Haftstellen gelten.