Proximity and Flux Pinning Effects in Superconductor-ferromagnet Hybrids

Proximity and Flux Pinning Effects in Superconductor-ferromagnet Hybrids
Author: Xavier Palermo
Publisher:
Total Pages: 0
Release: 2019
Genre:
ISBN:
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Superconductor-ferromagnet hybrid systems often bring about new physics and may as well be useful to design new non-volatile, high-density memory devices for superconducting electronics.In this thesis, we study two different types of SF hybrids, each following a possible approach to memory devices, but focusing on fundamental aspects. One is about the proximity effect in oxide heterostructures. In these, triplet correlations appear, that are both superconducting and spin-polarized. These enable using effects from spintronics like GMR, but are also very dependent on interface properties. We investigated these in SFS oxide trilayers by conductance measurements. These showed oscillations which may, in part, be related to these triplet states. We also observed that interface effects affect the electronic properties of the ferromagnet, especially when that layer is thin. Another type of interaction occurs through stray magnetic fields from the domain structures. Recent theoretical proposals suggested that small swirling spin textures called skyrmions could similarly interact with superconductivity through this mechanism. We investigated such coupling in bilayers, in which the superconducting vortex dynamics dominate the transport properties. We found that the presence of skyrmions and domains alike enhances the critical current. It also leads to an unusual Hall effect in the superconducting state. Most of these properties can be explained qualitatively in terms of vortex pinning and guided motion.

Superconductors at the Nanoscale

Superconductors at the Nanoscale
Author: Roger Wördenweber
Publisher: Walter de Gruyter GmbH & Co KG
Total Pages: 590
Release: 2017-09-11
Genre: Science
ISBN: 3110456249
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By covering theory, design, and fabrication of nanostructured superconducting materials, this monograph is an invaluable resource for research and development. Examples are energy saving solutions, healthcare, and communication technologies. Key ingredients are nanopatterned materials which help to improve the superconducting critical parameters and performance of superconducting devices, and lead to novel functionalities. Contents Tutorial on nanostructured superconductors Imaging vortices in superconductors: from the atomic scale to macroscopic distances Probing vortex dynamics on a single vortex level by scanning ac-susceptibility microscopy STM studies of vortex cores in strongly confined nanoscale superconductors Type-1.5 superconductivity Direct visualization of vortex patterns in superconductors with competing vortex-vortex interactions Vortex dynamics in nanofabricated chemical solution deposition high-temperature superconducting films Artificial pinning sites and their applications Vortices at microwave frequencies Physics and operation of superconducting single-photon devices Josephson and charging effect in mesoscopic superconducting devices NanoSQUIDs: Basics & recent advances Bi2Sr2CaCu2O8 intrinsic Josephson junction stacks as emitters of terahertz radiation| Interference phenomena in superconductor-ferromagnet hybrids Spin-orbit interactions, spin currents, and magnetization dynamics in superconductor/ferromagnet hybrids Superconductor/ferromagnet hybrids

Flux Pinning in Superconductors

Flux Pinning in Superconductors
Author: Teruo Matsushita
Publisher: Springer Nature
Total Pages: 506
Release: 2022-08-31
Genre: Technology & Engineering
ISBN: 3030946398
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This book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Recent developments of critical current properties in various high-Tc superconductors and MgB2 are introduced. The 3rd edition has been thoroughly updated, with a new chapter on critical state model. The mechanism of irreversible properties is discussed in detail. The author provides calculations of pinning loss by the equation of motion of flux lines in the pinning potential and hysteresis loss. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. This book aims for graduate students and researchers studying superconductivity as well as engineers working in electric utility industry.

Magnetic Imaging of Micrometer and Nanometer-size Magnetic Structures and Their Flux-Pinning Effects on Superconducting Thin Films

Magnetic Imaging of Micrometer and Nanometer-size Magnetic Structures and Their Flux-Pinning Effects on Superconducting Thin Films
Author: Ali E. Ozmetin
Publisher:
Total Pages:
Release: 2010
Genre:
ISBN:
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In this work the interactions between neighboring superconducting thin film and ferromagnetic structures, i.e. superconductor-ferromagnet hybrid systems, were studied. A type-II superconducting thin film (Pb82Bi12), was deposited in close proximity to various ferromagnetic structures. These magnetic structures include: (i) alternating iron-brass shims of 275 mu m period, (ii) an array of 4 mu m wide Co stripes with smaller period (9 mu m), (iii) a square array of 50nm diameter, high aspect ratio (5-7) Ni rods with 250nm period. Measurements of critical transport current (IC), resistance (RH(T)) and second critical field (HC2) are reported. A variety of novel effects (enhancement of (IC) and (HC2), matching field effect, field compensation effect, and large hysteresis) are also reported. Using measurements on thin superconducting films atop a Co stripe array with a 9 mu m period, a superconductor-ferromagnet hybrid device (a mechanical superconducting persistent switch) is proposed. In addition, scanning Hall probe microscopy (SHPM) and other imaging techniques were used to characterize the magnetic properties of the systems mentioned. The SHPM was also used to acquire B-H and M-H curves. An additional sharp magnetic needle and electromagnetic coil assembly intended for micromanipulation of small magnetic particles and individual cells was also characterized.

Nanoscience and Engineering in Superconductivity

Nanoscience and Engineering in Superconductivity
Author: Victor Moshchalkov
Publisher: Springer Science & Business Media
Total Pages: 407
Release: 2010-11-10
Genre: Science
ISBN: 364215137X
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For emerging energy saving technologies superconducting materials with superior performance are needed. Such materials can be developed by manipulating the "elementary building blocks" through nanostructuring. For superconductivity the "elementary blocks" are Cooper pair and fluxon (vortex). This book presents new ways how to modify superconductivity and vortex matter through nanostructuring and the use of nanoscale magnetic templates. The basic nano-effects, vortex and vortex-antivortex patterns, vortex dynamics, Josephson phenomena, critical currents, and interplay between superconductivity and ferromagnetism at the nanoscale are discussed. Potential applications of nanostructured superconductors are also presented in the book.

Sixteenth International Conference Zaragoza-Pau on Mathematics and its Applications

Sixteenth International Conference Zaragoza-Pau on Mathematics and its Applications
Author: José Luis Gracia
Publisher: Prensas de la Universidad de Zaragoza
Total Pages: 228
Release: 2024-02-08
Genre: Mathematics
ISBN: 8413407915
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The International Conference Zaragoza-Pau on Mathematics and its Applications was organized by the Departamento de Matem.tica Aplicada, the Departamento de M.todos Estad.sticos and the Departamento de Matem.ticas, all of them from the Universidad de Zaragoza (Spain), and the Laboratoire de Math.matiques et de leurs Applications, from the Universit. de Pau et des Pays de l’Adour (France). This conference has been held every two years since 1989. The aim of this conference is to present recent advances in Applied Mathematics, Statistics and Pure Mathematics, putting special emphasis on subjects linked to petroleum engineering and environmental problems. The Sixteenth Conference took place in Jaca (Spain) from 7th to 9th September 2022. The official opening ceremony was graced by the presence of the Vice–Chancellor for Academic Policy of the University of Zaragoza, D. Jos. .ngel Castellanos G.mez, and Vice–Chancellor of the Research Commission of the University of Pau, Mme. Isabelle Baraille. During those three days, 111 mathematicians, coming from different universities, research institutes or the industrial sector, attended 8 plenary lectures, 69 contributed talks and a poster session with 7 posters. We note that in this edition there were 11 mini-symposia, five of them co-organized by colleagues from the Universidad de Zaragoza and the Universit. de Pau et des Pays de l’Adour.

Proximity Effect in Superconductor-ferromagnet Systems

Proximity Effect in Superconductor-ferromagnet Systems
Author: Jian Zhu
Publisher:
Total Pages: 137
Release: 2010
Genre:
ISBN: 9781124354293
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The proximity effect in superconductor (SC) - ferromagnet (FM) system produces many interesting phenomena due to the interplay between two competing orderings, superconductivity and ferromagnetism. This dissertation studies the influence of the orientation of magnetic moments on the superconducting transition temperature (Tc̳) in FM/SC/FM sandwiched structures. The superconducting transition temperature of a FM/SC/FM spin valve depends on the mutual orientation of the magnetic moments of the ferromagnetic layers. This phenomenon, called the spin switch effect, has been previously observed in FM/SC/FM systems as a Tc̳ difference between parallel and antiparallel configurations of the ferromagnetic layers. Both standard (TP̳c̳ TA̳P̳c̳) and inverse (TP̳c̳ TA̳P̳̳c̳) spin switch effects have been reported in different superconducting spin valve systems but the origin of the inverse spin switch effect was not understood. In this dissertation, a discovery of the coexistence of the standard and inverse spin switch effects in Ni1 Fe19 /Nb/Ni1 Fe19 /Ir25 Mn--5 spin valves is described. The measurements reveal that the inverse spin switch effect originates from dissipative flow of vortices induced by stray magnetic field of magnetostatically coupled Neel domain wall pairs in the ferromagnetic layers. This dissertation also studies the Tc̳ of FM/SC/FM sandwiched systems with noncollinear (neither parallel nor antiparallel) orientation of the magnetic moments of the ferromagnetic layers, where the odd triplet superconducting component is predicated to arise. Tc̳ in Cu48 Ni52 /Nb/Cu48 Ni52 trilayers as a function of the angle between the Cu48 Ni52 layer magnetizations is measured. The shape of the observed angular dependence ofTc̳ is in qualitative agreement with SC/FM proximity theories that account for the odd triplet component of the condensate, but large discrepancy in the magnitude is found.

The Oxford Handbook of Small Superconductors

The Oxford Handbook of Small Superconductors
Author: A. V. Narlikar
Publisher: Oxford University Press
Total Pages: 641
Release: 2017
Genre: Science
ISBN: 0198738161
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Mesoscopic superconductors achieve a level of smallness that reveals the dominance of strange quantum effects. In a world driven by the miniaturization of electronic device technology, small superconductors acquire great relevance and timeliness for the development of ground breaking novel quantum devices.