ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Electronic structure of FM|semiconductor|FM spin tunneling structures : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 5518-5520 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have calculated the electronic structure of the spin-dependent tunneling structures, Fe|Ge|Fe and Fe|GaAs|Fe, using first principles techniques. We find that there is a large charge transfer from the metal layer to the semiconductor layer; 0.21 electrons are transferred from Fe to Ge and 0.27 electrons are transferred from Fe to GaAs at each interface. The density of states of the interfacial metal layer is dramatically different from the other metal layers; there is a large peak in the density of states at the Fermi energy for the minority electrons. The electronic structure of the semiconductor layer is quite different for the majority and the minority spins although its total magnetic moment is negligible. Our results suggest that the theory of spin-dependent tunneling using the simple model of a potential barrier or a model based on densities of states taken from bulk band structures may not apply to these systems. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.364587
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    First principles calculations of electrical conductivity and giant magnetoresistance of periodic multilayers and spin valves (invited) : The 40th annual conference on magnetism and magnetic materials (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 5282-5287 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We used the Layer Korringa Kohn Rostoker technique to calculate the electronic structure of cobalt-copper multilayers and spin valves from first principles within the local spin density approximation. Using this electronic structure together with a phenomenological self-energy which may vary from layer to layer, we calculated the non-local layer-dependent conductivity by means of the Kubo linear response formalism. By calculating the majority and minority conductivities for parallel and anti-parallel alignment of the moments in the cobalt layers we determined the giant magnetoresistance (GMR). Several interesting features emerge from the calculations. When the scattering rates are relatively high, we find that the contributions to the GMR are largely non-local, with the largest contributions arising from changes in the currents carried in a cobalt plane next to copper due to fields sensed in the cobalt layer on the other side of copper. When scattering rates are relatively low (comparable to that of cobalt and copper at room temperature), there are important contributions to the GMR from local conduction in the copper layers. This effect arises from the fact that when the component of the majority spin electron momentum parallel to the layers exceeds a certain value, it gets trapped in the copper layers. If the scattering rate is lower in the copper than in the cobalt there is a significant enhancement in the majority spin conductivity and in the GMR. This effect is analogous to the channeling of light by an optical waveguide. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.362566
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Magnetic structure of the spin valve interface : The 6th joint magnetism and magnetic materials (MMM)−intermag conferenc (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6805-6807 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358135
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Theory of transport in inhomogeneous systems and application to magnetic multilayer systems : The 6th joint magnetism and magnetic materials (MMM)−intermag conferenc (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6808-6810 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A theory of the electrical conductivity of homogeneous random alloys based on the Korringa—Kohn—Rostoker coherent potential approximation (KKR-CPA) is generalized to treat an inhomogeneous alloy in which the concentrations of the constituent atoms can vary from site to site. A special case of such a system is an epitaxial multilayer system. We develop the theory for such systems and show how it can be implemented by using the layer Korringa—Kohn—Rostoker technique to calculate the electronic structure. Applications to magnetic multilayers and to the calculation of the giant magnetoresistance are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.358136
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Patterned heteroepitaxial processing applied to ZnSe and ZnS0.02Se0.98 on GaAs (001) (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3912-3917 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have demonstrated the patterned heteroepitaxial processing (PHP) approach for the removal of threading dislocations (TDs) from ZnSe and ZnS0.02Se0.98 on GaAs (001). PHP involves the growth of a continuous heteroepitaxial layer followed by postgrowth patterning and annealing. We found that the basic mechanism of TD removal by PHP is thermally activated dislocation motion in the presence of sidewalls. By studying the temperature dependence we showed that the activation energy for the annealing process (∼0.7 eV in ZnSe on GaAs) is consistent with dislocation motion by glide. We showed that there is a minimum mesa thickness required for the complete removal of TDs by PHP (∼3000 Å for 70 μm×70 μm mesas of ZnSe on GaAs). This is because the lateral forces acting on TDs are proportional to the mesa thickness. We also conducted a preliminary study of the mismatch dependence of PHP. Our results suggest that PHP removes TDs more effectively in the higher lattice mismatch system ZnSe/GaAs (001) than in the lower lattice mismatch system ZnS0.02Se0.98/GaAs (001). This is expected based on the mismatch dependence of the line tension forces in the misfit segments of dislocations. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1446227
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Solution to the Boltzmann equation for layered systems for current perpendicular to the planes (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5173-5175 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Present theories of giant magnetoresistance (GMR) for current perpendicular to the planes (CPP) are based on an extremely restricted solution to the Boltzmann equation that assumes a single free electron band structure for all layers and all spin channels. Within this model only the scattering rate changes from one layer to the next. This model leads to the remarkable result that the resistance of a layered material is simply the sum of the resistances of each layer. We present a solution to the Boltzmann equation for CPP for the case in which the electronic structure can be different for different layers. The problem of matching boundary conditions between layers is much more complicated than in the current in the planes (CIP) geometry because it is necessary to include the scattering-in term of the Boltzmann equation even for the case of isotropic scattering. This term couples different values of the momentum parallel to the planes. When the electronic structure is different in different layers there is an interface resistance even in the absence of intermixing of the layers. The size of this interface resistance is affected by the electronic structure, scattering rates, and thicknesses of nearby layers. For Co–Cu, the calculated interface resistance and its spin asymmetry is comparable to that measured at low temperature in sputtered samples. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.373285
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    A simple treatment of the "scattering-in" term of the Boltzmann equation for multilayers (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 5176-5178 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present a simple approximation for treating anisotropic scattering within the semiclassical Boltzmann equation for current in plane geometry in magnetic multilayers. This approximation can be used to qualitatively account for the forward scattering that is neglected in the lifetime approximation, and requires only one additional parameter. For the case of a bulk material its effect is a simple renormalization of the scattering rate. The simplicity of this term has allowed quick and simple solution to the Boltzmann equation for magnetic multilayers using realistic band structures. When we use the band structures for Cu|Co multilayers obtained from first-principles calculations, we find an increase in the resistance of the multilayer, compared to the solution without the scattering-in term, due to the higher scattering rates needed to fit the same bulk conductivities. The giant-magnetoresistance ratio is also changed when the vertex corrections are included. © 2000 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.373286
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    First principles modeling of magnetic random access memory devices (invited) (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 5834-5839 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Giant magnetoresistance (GMR) and spin-dependent tunneling may be used to make magnetic random access memory devices. We have applied first-principles based electronic structure techniques to understand these effects and in the case of GMR to model the transport properties of the devices. © 1999 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.369933
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Calculation of the canting angle dependence of the resistivity in Cu|Co spin valves : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4008-4010 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We consider the in-plane electrical conductivity of a spin valve, specifically, a system consisting of a copper slab between two cobalt slabs. We calculate the dependence of the resistivity on the canting angle, where the canting angle θ is defined as the angle between the magnetization vectors of two ferromagnetic slabs in a spin valve. To calculate the electronic structure, we utilize the layer-KKR formalism. Electron scattering by impurities, phonons, magnons, etc. is modeled using a layer and spin-dependent complex self-energy. Scattering rates are chosen to match Cu and Co resistivities. We assume a spin asymmetry scattering rate factor of 7 in Co, matching the Fermi-level minority-to-majority density-of-states ratio. No additional interfacial scattering is included. The nonlocal layer dependent conductivity is calculated using the Kubo–Greenwood formula for systems consisting of 3 and 7 monolayer fcc (111) Cu slabs in Co. We find electron channeling in Cu dominates the conductivity and at θ=π/2 the resistivity is increased by 4.9% and 2.3% from a linear 1−cos θ dependence. We find giant magnetoresistive GMR values of 64% and 36% for 3 and 7 monolayers of Cu, respectively. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.364922
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Local field and quantum effects for current perpendicular to planes in multilayers : The 41st annual conference on magnetism and magnetic materials (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 4576-4578 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The calculation of giant magnetoresistance and in general, of electron transport for multilayers in the case of current perpendicular to the planes (CPP) requires both the two-point conductivity and the solution to the local field problem. In this paper we present a solution to the local field problem at an interface using two approaches. In the first approach we find the semiclassical solution for the local field when there is a band mismatch between two sides of an interface, and examine the deviation of the total resistance from the result of "self-averaging," in the lowest order of the value of the potential step. In the second approach, we solve for the quantum correction to the local field through a numerical iterative scheme. The oscillations due to the quantum correction are surprisingly large, but their correction to the total resistance is remarkably small. Our results imply that the "self-averaging" of the resistance, which is usually assumed in analysis of CPP, is only approximate. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.365433
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...