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Author : Jitae Park
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (863 download)
Download or read book Spin Dynamics in 122-type Iron-based Superconductors written by Jitae Park and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 : Gerd Friemel
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (885 download)
Download or read book Itinerant Spin Dynamics in Iron-based Superconductors and Cerium-based Heavy-fermion Antiferromagnets written by Gerd Friemel and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 : 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 : 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 : Leland Weldon Harriger
Publisher :
ISBN 13 :
Total Pages : 196 pages
Book Rating : 4.:/5 (826 download)
Download or read book Magnetic Excitations in the Iron Based Superconductors written by Leland Weldon Harriger and published by . This book was released on 2012 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented within are neutron scattering studies detailing the spin dynamics of BaNi[subscript x]Fe2[subscript x]As2 for x = 0 (parent), 0.04 (underdoped), and 0.1 (optimal) dopings, and FeSe[subscript x]Te1[subscript x] for x = 0 (parent), 0.3 (underdoped), and 0.4 (optimal) dopings. These recently discovered Fe-based superconducting compounds are strikingly similar, in many respects, to the cuprate class of unconventional superconductors and share qualitatively similar phase diagrams consisting of a long range ordered magnetic ground state in the parents which, upon doping, is supplanted in favor of superconductivity. The dopings discussed herein allow us to tune through the phase diagram, beginning with long range ordered parents and ending with optimally doped superconductors with short range magnetic correlations. For BaFe2As2, the excitations in the ordered state are strongly damped and persist up to 300meV. Low energies excitations are centered around Q[subscript AMF] and disperse towards the zone boundary with increasing energy. Only scattering above 100meV is effected when warming above T[subscript N]. In underdoped x = 0.04 BaNi[subscript x]Fe2−[subscript x]As2, we find an order of magnitude reduction in the coupling between layers and a corresponding crossover from 3D to 2D magnetism. In coauthor work on optimal doped x = 0.1 BaNi[subscript x]Fe2−[subscript x]As2 we establish the existence of a 3D resonance mode in the superconducting state. Excitations at optimal doping above the resonance are very similar to the paramagnetic scattering observed in the parent and consists of diffuse scattering below 100meV while above this threshold the signal has similar dispersion, linewidths, and intensity as the ordered state. For FeTe, I discuss our existing efforts and data collection aimed at addressing issues associated with calculating the effective moment from Q, E-integrated data. Tuning through the phase diagram to the x = 0.3 underdoped FeSe[subscript x]Te1−[subscript x] system we find filamentary superconductivity with magnetic spectral weight sitting at both the AFM and nesting vector. Upon reaching x = 0.4 optimal doping, the scattering completely transfers over to the nesting vector and a 2D resonance mode appears below T[subscript c].
Author : Keith M. Taddei
Publisher :
ISBN 13 : 9781369000177
Total Pages : 236 pages
Book Rating : 4.0/5 (1 download)
Download or read book Magnetism in the Iron-based Superconductors written by Keith M. Taddei and published by . This book was released on 2016 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: With nearly innumerable applications, superconductivity stands as a holy grail in the research of quantum phenomena. Understanding the mechanism that begets the fabled pairing of electrons which leads to zero resistance is the most significant undertaking in order to bring to fruition all of superconductivity's splendor. Yet the interaction which couples electrons in the most promising family of superconductors known as unconventional superconductors, which show the highest Tc's and largest upper critical fields remains a mystery. Intense study over the past several decades on the cuprate superconductors has allowed for the identification of several candidate mechanisms --- cardinal of which is magnetic fluctuations --- however as of yet the question still remains. Recently, the discovery of the iron-based superconductors has provided another fruitful avenue through which this mechanism can be probed. Excitingly in these materials superconductivity not only arises near a magnetic instability - a situation which is expected to be particularly suited for engendering superconductivity should magnetic fluctuations be the pairing mechanism - but also exhibit the microscopic co-existence of the two presumably adversarial phenomena. In the work presented here the powerful techniques of neutron and x-ray diffraction will be used to study two particularly interesting members of this family: the intercalated iron-selenide CsxFe 2--xSe2 and two members of the iron-arsenide 122 family (BaFe2(As1--xPx)2 and Sr1--xNaxFe2As 2). Though isostructural at high temperatures, these two materials behave remarkably differently and the idiosyncratic manifestations of superconductivity and ordered magnetism in either give clues as to how the latter might stabilize the former. The iron-selenides will be shown to exhibit a complex phase space with phase separation leading to stabilization of magnetism and superconductivity in separate phases. The structure, behavior and complex vacancy ordering of this phase-separated state will be elucidated and the superconductivity attributed to a pseudo-stable minority phase. Detailed phase diagrams will be constructed for the related BaFe2(As1--xPx) 2 and Sr1--xNaxFe2 As2 compounds leading to a direct comparison of the effects driving of either doping regime. A strong magneto-elastic coupling will be established in both of these materials and a new magnetic phase will be mapped in Sr1--xNaxFe2As2. These observations will lead to a discussion of the role of magnetic fluctuations in the overall behavior of the material. The results of inelastic and elastic diffraction experiments will be combined with the results of the local probe M?ssbauer spectroscopy technique in order to determine magnetic fluctuations as the primary order parameter in the phase evolution of the iron-based superconductors, and therefore their importance in establishment of superconductivity as the ground state of these materials.
Author : Alice Elizabeth Taylor
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (879 download)
Download or read book Magnetic Dynamics in Iron-based Superconductors Probed by Neutron Spectroscopy written by Alice Elizabeth Taylor and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yong Zhang
Publisher : BoD – Books on Demand
ISBN 13 : 1803561106
Total Pages : 268 pages
Book Rating : 4.8/5 (35 download)
Download or read book High Entropy Materials written by Yong Zhang and published by BoD – Books on Demand. This book was released on 2023-01-18 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-Entropy Materials - Microstructures and Properties summarizes recent developments in multicomponent materials. It discusses properties, processing, modeling, and applications of high-entropy materials, including metallic alloys and oxides. It also discusses solidification, sputtering, cryogenic treatments, CALPHAD methodology, biomedical implants, Fe-based superconductors, Fe-rich high-entropy alloys, and more.
Author : Qi-Miao Si
Publisher :
ISBN 13 :
Total Pages : 282 pages
Book Rating : 4.:/5 (254 download)
Download or read book Spin Dynamics in the Normal State of the High Temperature Superconductors written by Qi-Miao Si and published by . This book was released on 1991 with total page 282 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 : 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.
Author :
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (682 download)
Download or read book Spin Dynamics and Implications for Superconductivity written by and published by . This book was released on 1993 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt: We review the spin dynamics of the normal state of the cuprates with special emphasis on neutron data in both the YBa2Cu3O{sub 7-{delta}} and La{sub 2-x}Sr(subscript x)CuO4 systems. When realistic models of the Fermi surface shapes are incorporated, along with a moderate degree of spin fluctuations, we find good semi-quantiative agreement with experiment for both cuprates. Building on the success of this Fermi-liquid-based scheme, we explore the implications for d-wave pairing from a number of vantage points. We conclude that our present experimental and theoretical understanding is inadequate to confirm or refute the d-wave scenario.
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:
Author : Hemke Maeter
Publisher :
ISBN 13 :
Total Pages : 174 pages
Book Rating : 4.:/5 (827 download)
Download or read book Muon Spin Relaxation and Rotation of Iron-based Superconductors written by Hemke Maeter and published by . This book was released on 2012 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yu Gong
Publisher :
ISBN 13 : 9781303533020
Total Pages : 264 pages
Book Rating : 4.5/5 (33 download)
Download or read book Time Resolved Optical Studies of Spin and Quasiparticle Dynamics in Ferromagnetic Thin Films and Superconductors written by Yu Gong and published by . This book was released on 2013 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the studies of spin and quasiparticle dynamics in ferromagnetic thin films and iron based superconductors by ferromagnetic resonance (FMR) and time-resolved pump-probe optical techniques.
