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Author : Junhua Zhang
Publisher :
ISBN 13 :
Total Pages : 119 pages
Book Rating : 4.:/5 (761 download)
Download or read book Theory of Spin-fluctuation Induced Superconductivity in Iron-based Superconductors written by Junhua Zhang and published by . This book was released on 2011 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Spin-fluctuation Induced Superconductivity in Iron-based Superconductors written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation we focus on the investigation of the pairing mechanism in the recently discovered high-temperature superconductor, iron pnictides. Due to the proximity to magnetic instability of the system, we considered short-range spin fluctuations as the major mediating source to induce superconductivity. Our calculation supports the magnetic fluctuations as a strong candidate that drives Cooper-pair formation in this material. We find the corresponding order parameter to be of the so-called ss-wave type and show its evolution with temperature as well as the capability of supporting high transition temperature up to several tens of Kelvin. On the other hand, our itinerant model calculation shows pronounced spin correlation at the observed antiferromagnetic ordering wave vector, indicating the underlying electronic structure in favor of antiferromagnetic state. Therefore, the electronic degrees of freedom could participate both in the magnetic and in the superconducting properties. Our work shows that the interplay between magnetism and superconductivity plays an important role to the understanding of the rich physics in this material. The magnetic-excitation spectrum carries important information on the nature of magnetism and the characteristics of superconductivity. We analyze the spin excitation spectrum in the normal and superconducting states of iron pnictides in the magnetic scenario. As a consequence of the sign-reversed gap structure obtained in the above, a spin resonance mode appears below the superconducting transition temperature. The calculated resonance energy, scaled with the gap magnitude and the magnetic correlation length, agrees well with the inelastic neutron scattering (INS) measurements. More interestingly, we find a common feature of those short-range spin fluctuations that are capable of inducing a fully gapped ss state is the momentum anisotropy with elongated span along the direction transverse to the antiferromagnetic momentum transfer. This calculated intrinsic anisotropy exists both in the normal and in the superconducting state, which naturally explains the elliptically shaped magnetic responses observed in INS experiments. Our detailed calculation further shows that the magnetic resonance mode exhibits an upward dispersion-relation pattern but anisotropic along the transverse and longitudinal directions. We also perform a qualitative analysis on the relationship between the anisotropic momentum structure of the magnetic fluctuations and the stability of superconducting phase by intraorbital but interband pair scattering to show the consistency of the magnetic mechanism for superconductivity. As discussed for cuprates, an important identification of the mediating boson is from the fermionic spectrum. We study the spectral function in the normal and superconducting state. Not only do we extract the gap magnitude on the electron- and hole-pockets to show the momentum structure of the gap, but also find a peak-dip-hump feature in the electron spectrum, which reflects the feedback from the spin excitations on fermions. This serves as an interpretation of the kink structure observed in ARPES measurements.
Author : Aliaksei Charnukha
Publisher : Springer Science & Business Media
ISBN 13 : 3319011928
Total Pages : 139 pages
Book Rating : 4.3/5 (19 download)
Download or read book Charge Dynamics in 122 Iron-Based Superconductors written by Aliaksei Charnukha and published by Springer Science & Business Media. This book was released on 2013-09-12 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis combines highly accurate optical spectroscopy data on the recently discovered iron-based high-temperature superconductors with an incisive theoretical analysis. Three outstanding results are reported: (1) The superconductivity-induced modification of the far-infrared conductivity of an iron arsenide with minimal chemical disorder is quantitatively described by means of a strong-coupling theory for spin fluctuation mediated Cooper pairing. The formalism developed in this thesis also describes prior spectroscopic data on more disordered compounds. (2) The same materials exhibit a sharp superconductivity-induced anomaly for photon energies around 2.5 eV, two orders of magnitude larger than the superconducting energy gap. The author provides a qualitative interpretation of this unprecedented observation, which is based on the multiband nature of the superconducting state. (3) The thesis also develops a comprehensive description of a superconducting, yet optically transparent iron chalcogenide compound. The author shows that this highly unusual behavior can be explained as a result of the nanoscopic coexistence of insulating and superconducting phases, and he uses a combination of two complementary experimental methods - scanning near-field optical microscopy and low-energy muon spin rotation - to directly image the phase coexistence and quantitatively determine the phase composition. These data have important implications for the interpretation of data from other experimental probes.
Author : Nan Lin Wang
Publisher : CRC Press
ISBN 13 : 9814303224
Total Pages : 564 pages
Book Rating : 4.8/5 (143 download)
Download or read book Iron-based Superconductors written by Nan Lin Wang and published by CRC Press. This book was released on 2012-11-19 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: From fundamental physics point of view, iron-based superconductors have properties that are more amenable to band structural calculations. This book reviews the progress made in this fascinating field. With contributions from leading experts, the book provides a guide to understanding materials, physical properties, and superconductivity mechanism aspects, and is important for students and beginners to have an overall view of the recent progress in this active field.
Author : Peter D. Johnson
Publisher : Springer
ISBN 13 : 3319112546
Total Pages : 452 pages
Book Rating : 4.3/5 (191 download)
Download or read book Iron-Based Superconductivity written by Peter D. Johnson and published by Springer. This book was released on 2015-01-06 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents an in-depth review of experimental and theoretical studies on the newly discovered Fe-based superconductors. Following the Introduction, which places iron-based superconductors in the context of other unconventional superconductors, the book is divided into three sections covering sample growth, experimental characterization, and theoretical understanding. To understand the complex structure-property relationships of these materials, results from a wide range of experimental techniques and theoretical approaches are described that probe the electronic and magnetic properties and offer insight into either itinerant or localized electronic states. The extensive reference lists provide a bridge to further reading. Iron-Based Superconductivity is essential reading for advanced undergraduate and graduate students as well as researchers active in the fields of condensed matter physics and materials science in general, particularly those with an interest in correlated metals, frustrated spin systems, superconductivity, and competing orders.
Author : Ferdinando Mancini
Publisher : Springer
ISBN 13 : 3319561170
Total Pages : 197 pages
Book Rating : 4.3/5 (195 download)
Download or read book The Iron Pnictide Superconductors written by Ferdinando Mancini and published by Springer. This book was released on 2017-05-25 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers different aspects of the physics of iron-based superconductors ranging from the theoretical, the numerical and computational to the experimental ones. It starts from the basic theory modeling many-body physics in Fe-superconductors and other multi-orbital materials and reaches up to the magnetic and Cooper pair fluctuations and nematic order. Finally, it offers a comprehensive overview of the most recent advancements in the experimental investigations of iron based superconductors.
Author : Karl-Heinz Bennemann
Publisher : Springer Science & Business Media
ISBN 13 : 9783540442325
Total Pages : 1166 pages
Book Rating : 4.4/5 (423 download)
Download or read book The Physics of Superconductors written by Karl-Heinz Bennemann and published by Springer Science & Business Media. This book was released on 2004-04-07 with total page 1166 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume of a comprehensive two-volume treatise on superconductivity that represents the first such publication since the earlier widely acclaimed books by R. Parks. It systematically reviews the basic physics and recent advances in the field. Leading researchers describe the state of the art in conventional phonon-induced superconductivity, high-Tc superconductivity, and in novel superconductivity, including triplet pairing in the ruthenates. The second volume is largely concerned with novel superconductors, such as heavy-fermion metals and organic materials, and also includes granular superconductors. Important new results on current problems are presented in a manner designed to stimulate further research. Numerous illustrations, diagrams and tables make this book especially useful as a reference work for students, teachers and researchers. Volume 1 treats Conventional and High-Tc Superconductors (3-540-43883-1).
Author : Sergei Kruchinin
Publisher : World Scientific
ISBN 13 : 9811234531
Total Pages : 306 pages
Book Rating : 4.8/5 (112 download)
Download or read book Modern Aspects Of Superconductivity: Theory Of Superconductivity (Second Edition) written by Sergei Kruchinin and published by World Scientific. This book was released on 2021-04-14 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is devoted to superconductivity, which is one of the most interesting problems in physics. In accordance with the outline of the book, it treats the key problems in the field of superconductivity, in particular, it discusses the mechanism(s) of superconductivity. This book is useful for researchers and graduate students in the fields of solid state physics, quantum field theory, and many-body theory.
Download or read book Interplay Between Superconductivity and Magnetism in Iron-based Superconductors written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This proposal is for theoretical work on strongly correlated electron systems, which are at the center of experimental and theoretical activities in condensed-matter physics. The interest to this field is driven fascinating variety of observed effects, universality of underlying theoretical ideas, and practical applications. I propose to do research on Iron-based superconductors (FeSCs), which currently attract high attention in the physics community. My goal is to understand superconductivity and magnetism in these materials at various dopings, the interplay between the two, and the physics in the phase in which magnetism and superconductivity co-exist. A related goal is to understand the origin of the observed pseudogap-like behavior in the normal state. My research explores the idea that superconductivity is of electronic origin and is caused by the exchange of spin-fluctuations, enhanced due to close proximity to antiferromagnetism. The multi-orbital/multi-band nature of FeSCs opens routes for qualitatively new superconducting states, particularly the ones which break time-reversal symmetry. By all accounts, the coupling in pnictdes is below the threshold for Mott physics and I intend to analyze these systems within the itinerant approach. My plan is to do research in two stages. I first plan to address several problems within weak-coupling approach. Among them: (i) what sets stripe magnetic order at small doping, (ii) is there a preemptive instability into a spin-nematic state, and how stripe order affects fermions; (iii) is there a co-existence between magnetism and superconductivity and what are the system properties in the co-existence state; (iv) how superconductivity emerges despite strong Coulomb repulsion and can the gap be s-wave but with nodes along electron FSs, (v) are there complex superconducting states, like s+id, which break time reversal symmetry. My second goal is to go beyond weak coupling and derive spin-mediated, dynamic interaction between fermions, understand what sets the upper scale for attractive interaction, compute T_c, and then obtain and solve matrix non-linear gap equation for spin-mediated pairing and study various feedbacks from the pairing on fermions on ARPES spectra, optical and thermal conductivity, and other observables, The problems I have chosen are quite generic, and the understanding of magnetically-mediated superconductivity in the strong-coupling regime will not only advance the theory of superconductivity in FeSCs, but will contribute to a generic understanding of the pairing of fermions near quantum-critical points -- the problems ranging from s-wave pairing by soft optical phonons to to color superconductivity of quarks mediated by a gluon exchange.
Author : Frank Essenberger
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (935 download)
Download or read book Density Functional Theory for Superconductors written by Frank Essenberger and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superconductivity; spin-fluctuations; density functional theory; iron based superconductors
Author : Heshmatollah Yavari
Publisher : BoD – Books on Demand
ISBN 13 : 1789840651
Total Pages : 110 pages
Book Rating : 4.7/5 (898 download)
Download or read book On the Properties of Novel Superconductors written by Heshmatollah Yavari and published by BoD – Books on Demand. This book was released on 2020-07-29 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the discovery of superconductivity, a great number of theoretical and experimental efforts have been made to describe this new phase of matter that emerged in many body systems. In this regard, theoretical models have been presented; the most famous of which was the BCS theory that can only describe conventional superconductors. With the discovery of new class superconductors, the superconducting mechanism became a new challenge in the field of condensed matter physics. This unexpected discovery opened a new area in the history of superconductivity, and experimental researchers started trying to find new compounds in this class of superconductors. These superconductors are often characterized by the anisotropic character in the superconducting gap function with nodes along a certain direction in the momentum space. Since the pairing interaction has an important role in the superconducting gap structure, its determination is very important to explain the basic pairing mechanism.In this regard, this book includes valuable theoretical and experimental discussions about the properties of superconductors. Here you will find valuable research describing the properties of unconventional superconductors.
Author : Ken Nakatsukasa
Publisher :
ISBN 13 :
Total Pages : 153 pages
Book Rating : 4.:/5 (111 download)
Download or read book Low Energy Quasiparticle Excitations in Cuprates and Iron-based Superconductors written by Ken Nakatsukasa and published by . This book was released on 2018 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microscopic properties of the phonon mediated conventional superconductors are well explained by the Bardeen-Cooper-Schrieer (BCS) theory. However, a comprehensive description of the unconventional superconductivity such as the cuprates and iron-based superconductors is still under considerable debate. One of the theories proposed for explaining the pairing mechanism is the spin fluctuation exchange perhaps playing a leading role in inducing the unconventional superconductivity[1]. These materials are thought to be unconventional because they share certain commonalities that are absent in the conventional superconductors. The materials possess variety of phases upon doping including the superconductivity residing in close proximity to magnetism. They show an anisotropic superconducting order parameter. The transition temperatures tend to be higher than those predicted by the conventional electron-phonon couplings. These observations differ from the conventional superconductors indicating that the electron-phonon interactions may be non-factors or play a minimal role in paring. However, a significant phonon renormalization interpreted from photoemission spectroscopy[2], a pronounced isotope effect in cuprates[3], and the emergence of the replica band due to strong forward scattering phonons[4] raise questions regarding the role of phonons in these magnetic superconductors. McMillan and Rowell have studied the low energy excitations seen from a tunneling experiment to prove the electron-phonon coupling was indeed driving the superconductivity, and thus validated the BCS theory[5]. If the unconventional pairing is explained by the exchange of bosons, then one could use the extended version of the BCS theory such as the Eliashberg theory to describe properties of the superconductivity. In the present analysis, we have investigated the low energy features seen in various unconventional superconductors using a fully self-consistent algorithm. We find that the bosonic excitation picture has correctly explained many experimental features, though there were properties. The present analysis has enlightened the picture that the spin fluctuation exchange plays a pivotal role in mediating the pairing; we may further argue that the phonons can play an important role in renormalizing the electronic structure in cuprates; additionally, the forward scattering phonons can coexist with the spin fluctuation exchange to greatly enhance the transition temperature in a selected layered materials.
Author : Dirk Manske
Publisher : Springer Science & Business Media
ISBN 13 : 9783540212294
Total Pages : 244 pages
Book Rating : 4.2/5 (122 download)
Download or read book Theory of Unconventional Superconductors written by Dirk Manske and published by Springer Science & Business Media. This book was released on 2004-06-25 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents a theory for unconventional superconductivity driven by spin excitations. Using the Hubbard Hamiltonian and a self-consistent treatment of the spin excitations, the interplay between magnetism and superconductivity in various unconventional superconductors is discussed. In particular, the monograph applies this theory for Cooper-pairing due to the exchange of spin fluctuations to the case of singlet pairing in hole- and electron-doped high-Tc superconductors, and to triplet pairing in Sr2RuO4. Within the framework of a generalized Eliashberg-like treatment, calculations of both many normal and superconducting properties as well as elementary excitations are performed. The results are related to the phase diagrams of the materials which reflect the interaction between magnetism and superconductivity.
Author : Mircea Crisan
Publisher : World Scientific
ISBN 13 : 9814531820
Total Pages : 312 pages
Book Rating : 4.8/5 (145 download)
Download or read book Theory Of Superconductivity written by Mircea Crisan and published by World Scientific. This book was released on 1989-10-01 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses the most important aspects of the theory. The phenomenological model is followed by the microscopic theory of superconductivity, in which modern formalism of the many-body theory is used to treat most important problems such as superconducting alloys, coexistence of superconductivity with the magnetic order, and superconductivity in quasi-one-dimensional systems. It concludes with a discussion on models for exotic and high temperature superconductivity. Its main aim is to review, as complete as possible, the theory of superconductivity from classical models and methods up to the 1987 results on high temperature superconductivity.
Author : George Reiter
Publisher : Springer Science & Business Media
ISBN 13 : 1468474901
Total Pages : 359 pages
Book Rating : 4.4/5 (684 download)
Download or read book Dynamics of Magnetic Fluctuations in High-Temperature Superconductors written by George Reiter and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: This NATO Advanced Research Workshop was held at a time when there was little consensus as to the mechanism for high temperature superconductivity, in the context of a world undergoing major changes in its political alignments and sense of the possibility for the future. It was characterized by generosity in the sharing of our uncertainties and speculations, as was appropriate for both the subject matter and the context. The workshop was organized, of necessity around the experimental work, as is this volume. Where the theoretical work is directly relevant to particular experiments, it is included in the appropriate sections with them. Most of the participants felt strongly that magnetic fluctuations played an important role in the mechanism for high T c, although with the exception of the IlS R work reported by Luke showing results inconsistent with the anyon picture, and the work on flux phases by Lederer, the mechanism remained an issue in the background. A major focus was the phenomenological interpretation of the NMR data.
Author : Karl-Heinz Bennemann
Publisher : Springer Science & Business Media
ISBN 13 : 3642556752
Total Pages : 974 pages
Book Rating : 4.6/5 (425 download)
Download or read book The Physics of Superconductors written by Karl-Heinz Bennemann and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first volume of a comprehensive two-volume treatise on superconductivity that represents the first such publication since the earlier work by R. Parks. It systematically reviews the basic physics and recent advances in the field. Leading researchers describe the state of the art in conventional phonon-induced superconductivity, high-Tc superconductivity, and novel superconductivity. After an introduction and historical overview, the leaders in the special fields of research give a comprehensive survey of the basics and the state of the art in chapters covering the entire field of superconductivity, including conventional and unconventional superconductors. Important new results are reported in a manner intended to stimulate further research. Numerous illustrations, diagrams and tables make this book especially useful as a reference work for students, teachers, and researchers. The second volume treats novel superconductors.
Author : V.P. Mineev
Publisher : CRC Press
ISBN 13 : 9789056992095
Total Pages : 204 pages
Book Rating : 4.9/5 (92 download)
Download or read book Introduction to Unconventional Superconductivity written by V.P. Mineev and published by CRC Press. This book was released on 1999-09-21 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Unconventional superconductivity (or superconductivity with a nontrivial Cooper pairing) is believed to exist in many heavy-fermion materials as well as in high temperature superconductors, and is a subject of great theoretical and experimental interest. The remarkable progress achieved in this field has not been reflected in published monographs and textbooks, and there is a gap between current research and the standard education of solid state physicists in the theory of superconductivity. This book is intended to meet this information need and includes the authors' original results.
