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Book Low Temperature Scanning Tunneling Spectroscopy of Proximity Effect Junctions Formed on the Layered Superconductors NbSe2 and Bi2Sr2Ca1Cu2O8

Download or read book Low Temperature Scanning Tunneling Spectroscopy of Proximity Effect Junctions Formed on the Layered Superconductors NbSe2 and Bi2Sr2Ca1Cu2O8 written by Anthony D. Truscott and published by . This book was released on 1999 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Principles of Electron Tunneling Spectroscopy

Download or read book Principles of Electron Tunneling Spectroscopy written by E. L. Wolf and published by Oxford University Press. This book was released on 2012 with total page 617 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron tunnelling spectroscopy as a research tool has strongly advanced understanding of superconductivity. This book explains the physics and instrumentation behind the advances illustrated in beautiful images of atoms, rings of atoms and exotic states in high temperature superconductors, and summarizes the state of knowledge that has resulted.

Book High Temperature Superconductors

Download or read book High Temperature Superconductors written by Ajay Kumar Saxena and published by Springer Science & Business Media. This book was released on 2012-07-10 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the current knowledge about superconductivity in high Tc cuprate superconductors. There is a large scientific interest and great potential for technological applications. The book discusses all the aspects related to all families of cuprate superconductors discovered so far. Beginning with the phenomenon of superconductivity, the book covers: the structure of cuprate HTSCs, critical currents, flux pinning, synthesis of HTSCs, proximity effect and SQUIDs, possible applications of high Tc superconductors and theories of superconductivity. Though a high Tc theory is still awaited, this book describes the present scenario and BCS and RVB theories. The second edition was significantly extended by including film-substrate lattice matching and buffer layer considerations in thin film HTSCs, brick-wall microstructure in the epitaxial films, electronic structure of the CuO2 layer in cuprates, s-wave and d-wave coupling in HTSCs and possible scenarios of theories of high Tc superconductivity.

Book The Oxford Handbook of Small Superconductors

Download or read book The Oxford Handbook of Small Superconductors written by A. V. Narlikar and published by Oxford University Press. This book was released on 2017-03-09 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: This handbook is about a remarkable set of materials that are technically referred to as "mesoscopic superconductors", which for all practical purposes are tiny or small in their dimensions, ranging from a few micrometers down to a nanometer. At this level of smallness, the superconducting properties are dramatically changed, showing the dominance of quantum effects. Ground breaking research studies of small superconductors have emerged, and in a world obsessed with miniaturization of electronic device technology, small superconductors acquire even greater relevance and timeliness for the development of exciting novel quantum devices. The chapters, contributed by noted researchers and frontrunners in the field from 15 countries, are presented in three parts, namely progress in basic studies, materials specific research, and advances in nanodevices. The contents of the handbook should be of immediate interest to advanced level university students and researchers particularly in physics, materials science, nanoscience and engineering departments. Various reviews and overviews appearing in the book should answer the queries and curiosities of non-specialists interested in nanoscale superconductivity. At the start, the book carries an extended introduction for readers new to the field. The book should also appeal to scientists and engineers from electronic industries interested in knowing the current status of the theory, manufacture, and future of mesoscopic superconductors. In doing so, this volume offers the opportunity to engage with cutting edge research in one of the most exciting fields of physics today and tomorrow.

Book Proximity in Hybrid Superconductor Ferromagnetic Structures

Download or read book Proximity in Hybrid Superconductor Ferromagnetic Structures written by Makram Abd El Qader and published by . This book was released on 2016 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The coexistence of superconductivity and ferromagnetic orders has been the subject of study for many years. It well known that these materials possess two competing order parameters; however the two order parameters can coexist under special circumstances inducing interesting physical phenomena. In recent years the demand of ultra-low-power, high density cryogenic memories has brought considerable interest to integrate superconducting and magnetic thin films in one structure to produce novel memory elements. The operation of the device depends on the unusual electronic properties associated with the Superconductor (S) /Ferromagnetic (F) proximity effect. Niobium (Nb) based Josephson junction devices were fabricated with barriers containing two ferromagnetic layers separated by a normal metal space layer. In device operation, electrons in the superconductor are injected into the ferromagnets, causing the superconductor wavefunction to shift its phase and decay in amplitude. Such devices have two different states that depend on the relative magnetization of their ferromagnetic barrier layers, parallel or antiparallel. In these different states, the junctions have different phase shifts and critical currents. Superconducting circuits containing these devices can be designed to operate as memory cells using either one of these outputs. To quantify the shift in phase and amplitude decay of the wavefunction through a common ferromagnet, permalloy, a series of Nb/permalloy/Nb Josephson junctions with varying ferromagnetic layer thicknesses were fabricated. Data have shown that the optimal thickness of a fixed layer composed of permalloy is 2.4 nm, as it shifts the wavefunction phase to Ï0/2, its 0́−pivot point.0́+ If set to precisely this value, the free layer in SFNF'S junctions will switch the junction into either the 0 or Ï0 state depending on its magnetic orientation. To minimize the free-layer switching energy dilute Cu-permalloy alloy [Cu0.7(Ni80Fe20)0.3] with a low magnetic saturation (Ms of ~80 emu/cm3) was used as the free layer. These devices exhibit switching energies at small magnetic fields, demonstrating their potential use for low power non-volatile memory for superconductor circuits. Lastly, to study the proximity effect using other potentially-useful ferromagnetic layers, measurements were performed on Nb/F bilayers and Nb/F/AlOx/Al tunnel junctions with ferromagnets Ni8Fe19, Ni65Fe15Co20, and Pd1-xNix. The dependence of the critical temperature of the bilayers and density of states that propagated through the ferromagnetic layer were studied as a function of thickness. From this study, crucial magnetic and electrical parameters like magnetic coherence lengths (ÎlF), exchange energy (Eex), and the rate of shift in the wavefunction0́9s phase and amplitude as a function of thickness were determined.

Book Scanning Tunneling Microscopy and Spectroscopy Measurements of Superconductor Ferromagnet Hybrids

Download or read book Scanning Tunneling Microscopy and Spectroscopy Measurements of Superconductor Ferromagnet Hybrids written by Steven Alan Moore and published by . This book was released on 2015 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this thesis work is the study of the nanoscale electronic properties of magnetically coupled superconductor/ferromagnet hybrid structures using low-temperature scanning tunneling microscopy and spectroscopy (LT-STM/STS) under ultra-high vacuum conditions. There are a number of novel effects that can occur due to the non-homogenous magnetic field from the ferromagnet, which directly influence the global and local superconducting properties. These effects include the generation of vortices/anti-vortices by the non-uniform magnetic stray field, local modulations in the critical temperature, filamentary superconductivity close to the transition temperature, and superconducting channels that can be controlled by external magnetic fields. Prior to this dissertation the subject of superconductor/ferromagnet hybrid structures has been mainly studied using global measurements (such as transport and magnetization) or scanning probe techniques that are sensitive to the magnetic field. Scanning tunneling microscopy probes the local electronic density of states with atomic resolution, and therefore is the only technique that can study the emergence of superconductivity on the length scale of the coherence length. The novel results presented in this dissertation show that magnetically coupled superconductor/ferromagnet heterostructures offer the possibility to control and tune the strength and location of superconductivity and superconducting vortices, which has potential for promising technological breakthroughs in computing and power applications.

Book Topological Orders with Spins and Fermions

Download or read book Topological Orders with Spins and Fermions written by Laura Ortiz Martín and published by Springer. This book was released on 2019-07-11 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with topological orders from two different perspectives: from a condensed matter point of view, where topological orders are considered as breakthrough phases of matter; and from the emerging realm of quantum computation, where topological quantum codes are considered the most appealing platform against decoherence. The thesis reports remarkable studies from both sides. It thoroughly investigates a topological order called the double semion model, a counterpart of the Kitaev model but exhibiting richer quasiparticles as excitations. A new model for symmetry enriched topological order is constructed, which adds an onsite global symmetry to the double semion model. Using this topological phase, a new example of topological code is developed, the semion code, which is non-CSS, additive, non-Pauli and within the stabiliser formalism. Furthermore, the thesis analyses the Rashba spin-orbit coupling within topological insulators, turning the helical edge states into generic edges modes with potential application in spinstronics. New types of topological superconductors are proposed and the novel properties of the correspondingly created Majorana fermions are investigated. These Majorana fermions have inherent properties enabling braiding and the performance of logical gates as fundamental blocks for a universsal quantum computator.

Book Signatures of Topological Superconductors

Download or read book Signatures of Topological Superconductors written by Shu-Ping Lee and published by . This book was released on 2015 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Topological superconductors are particularly interesting in light of the active ongoing experimental efforts for realizing exotic physics such as Majorana zero modes. These systems have excitations with non-Abelian exchange statistics, which provides a path towards topological quantum information processing. Intrinsic topological superconductors are quite rare in nature. However, one can engineer topological superconductivity by inducing effective p-wave pairing in materials which can be grown in the laboratory. One possibility is to induce the proximity effect in topological insulators; another is to use hybrid structures of superconductors and semiconductors. The proposal of interfacing s-wave superconductors with quantum spin Hall systems provides a promising route to engineered topological superconductivity. Given the exciting recent progress on the fabrication side, identifying experiments that definitively expose the topological superconducting phase (and clearly distinguish it from a trivial state) raises an increasingly important problem. With this goal in mind, we proposed a detection scheme to get an unambiguous signature of topological superconductivity, even in the presence of ordinarily detrimental effects such as thermal fluctuations and quasiparticle poisoning. We considered a Josephson junction built on top of a quantum spin Hall material. This system allows the proximity effect to turn edge states in effective topological superconductors. Such a setup is promising because experimentalists have demonstrated that supercurrents indeed flow through quantum spin Hall edges. To demonstrate the topological nature of the superconducting quantum spin Hall edges, theorists have proposed examining the periodicity of Josephson currents respect to the phase across a Josephson junction. The periodicity of tunneling currents of ground states in a topological superconductor Josephson junction is double that of a conventional Josephson junction. In practice, this modification of periodicity is extremely difficult to observe because noise sources, such as quasiparticle poisoning, wash out the signature of topological superconductors. For this reason, We propose a new, relatively simple DC measurement that can compellingly reveal topological superconductivity in such quantum spin Hall/superconductor heterostructures. More specifically, We develop a general framework for capturing the junction's current-voltage characteristics as a function of applied magnetic flux. Our analysis reveals sharp signatures of topological superconductivity in the field-dependent critical current. These signatures include the presence of multiple critical currents and a non-vanishing critical current for all magnetic field strengths as a reliable identification scheme for topological superconductivity. This system becomes more interesting as interactions between electrons are involved. By modeling edge states as a Luttinger liquid, we find conductance provides universal signatures to distinguish between normal and topological superconductors. More specifically, we use renormalization group methods to extract universal transport characteristics of superconductor/quantum spin Hall heterostructures where the native edge states serve as a lead. Interestingly, arbitrarily weak interactions induce qualitative changes in the behavior relative to the free-fermion limit, leading to a sharp dichotomy in conductance for the trivial (narrow superconductor) and topological (wide superconductor) cases. Furthermore, we find that strong interactions can in principle induce parafermion excitations at a superconductor/quantum spin Hall junction. As we identify the existence of topological superconductor, we can take a step further. One can use topological superconductor for realizing Majorana modes by breaking time reversal symmetry. An advantage of 2D topological insulator is that networks required for braiding Majoranas along the edge channels can be obtained by adjoining 2D topological insulator to form corner junctions. Physically cutting quantum wells for this purpose, however, presents technical challenges. For this reason, I propose a more accessible means of forming networks that rely on dynamically manipulating the location of edge states inside of a single 2D topological insulator sheet. In particular, I show that edge states can effectively be dragged into the system's interior by gating a region near the edge into a metallic regime and then removing the resulting gapless carriers via proximity-induced superconductivity. This method allows one to construct rather general quasi-1D networks along which Majorana modes can be exchanged by electrostatic means. Apart from 2D topological insulators, Majorana fermions can also be generated in other more accessible materials such as semiconductors. Following up on a suggestion by experimentalist Charlie Marcus, I proposed a novel geometry to create Majorana fermions by placing a 2D electron gas in proximity to an interdigitated superconductor-ferromagnet structure. This architecture evades several manufacturing challenges by allowing single-side fabrication and widening the class of 2D electron gas that may be used, such as the surface states of bulk semiconductors. Furthermore, it naturally allows one to trap and manipulate Majorana fermions through the application of currents. Thus, this structure may lead to the development of a circuit that enables fully electrical manipulation of topologically-protected quantum memory. To reveal these exotic Majorana zero modes, I also proposed an interference scheme to detect Majorana fermions that is broadly applicable to any 2D topological superconductor platform.

Book Scanning Tunneling Spectroscopy of Bi Based High Temperature Superconductors

Download or read book Scanning Tunneling Spectroscopy of Bi Based High Temperature Superconductors written by Craig Martin Howald and published by . This book was released on 2002 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Point Contact Tunneling Spectroscopy in High Temperature Superconductors

Download or read book Point Contact Tunneling Spectroscopy in High Temperature Superconductors written by Qiang Huang and published by . This book was released on 1991 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Vortex Dynamics and Optical Vortices

Download or read book Vortex Dynamics and Optical Vortices written by Hector Perez-De-Tejada and published by BoD – Books on Demand. This book was released on 2017-03-01 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: The contents of the book cover a wide variety of topics related to the analysis of the dynamics of vortices and describe the results of experiments, computational modeling and their interpretation. The book contains 13 chapters reaching areas of physics in vortex dynamics and optical vortices including vortices in superfluid atomic gases, vortex laser beams, vortex-antivortex in ferromagnetic hybrids, and optical vortices illumination in chiral nanostructures. Also, discussions are presented on particle motion in vortex flows, on the simulation of vortex-dominated flows, on vortices in saturable media, on achromatic vortices, and on ultraviolet vortices. Fractal light vortices, coherent vortex beams, together with vortices in electric dipole radiation, and spin wave dynamics in magnetic vortices are examined as well.

Book Spin orbit Coupling Effects in Two Dimensional Electron and Hole Systems

Download or read book Spin orbit Coupling Effects in Two Dimensional Electron and Hole Systems written by Roland Winkler and published by Springer Science & Business Media. This book was released on 2003-10-10 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part provides a general introduction to the electronic structure of quasi-two-dimensional systems with a particular focus on group-theoretical methods. The main part of the monograph is devoted to spin-orbit coupling phenomena at zero and nonzero magnetic fields. Throughout the book, the main focus is on a thorough discussion of the physical ideas and a detailed interpretation of the results. Accurate numerical calculations are complemented by simple and transparent analytical models that capture the important physics.