Download or read book Superconductivity and Tunneling Spectroscopy of Amorphous Transition Metals Mo and Nb written by Dan Benjamin Kimhi and published by . This book was released on 1980 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1981 with total page 1370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Superconductivity of Transition Metals written by Sergeĭ Vasilʹevich Vonsovskiĭ and published by Springer. This book was released on 1982 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Superconductivity in D and F Band Metals written by David H. Douglass and published by American Institute of Physics. This book was released on 1972 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trend of Superconductivity in Amorphous Superconducting Transition Metals and Their Alloys written by and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A plausible interpretation for the trend of superconducting transition temperature T/sub c/ in amorphous transition metal TM alloys is presented from a chemical point of view. It is shown that the T/sub c/ behavior is not a reflection of the dependence of the atomic parameter eta on the number of electrons per atom, but rather due to two other effects. One is the changes in the density of states due to the mixing of antibonding and bonding states in the bcc amorphous metals. The other is an increase in the number of valence d electrons participating in the phonon-induced d-d coupling towards the mid series. (auth).

Download or read book Superconductivity in Amorphous Transition Metals written by Michael Moore Collver and published by . This book was released on 1971 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cryogenic Information Report written by and published by . This book was released on 1981 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Biweekly Cryogenics Current Awareness Service written by and published by . This book was released on 1980 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 698 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Energy Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1977 with total page 1104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dissertation Abstracts International written by and published by . This book was released on 1991 with total page 604 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Frontiers in Superconducting Materials written by Anant V. Narlikar and published by Springer Science & Business Media. This book was released on 2005-12-06 with total page 1122 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frontiers in Superconducting Materials gives a state-of-the-art report of the most important topics of the current research in superconductive materials and related phenomena. It comprises 30 chapters written by renowned international experts in the field. It is of central interest to researchers and specialists in Physics and Materials Science, both in academic and industrial research, as well as advanced students. It also addresses electronic and electrical engineers. Even non-specialists interested in superconductivity might find some useful answers.

Download or read book Superconductivity of Transition Metals written by S.V. Vonsovsky and published by Springer. This book was released on 1982 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book should fill a gap which has existed in the literature on supercon ductivity. There have been a number of excellent textbooks available on the phenomenon of superconductivity, which describe in detail the variety of ef fects connected with it and the mathematical techniques to deal with them properly. However, until now there has not been a textbook available in English which concentrates on the mate~ial aspects of superconductivity. This is a major shortcoming since most physicists working in the field of superconduc tivity are mainly concerned with specific materials and subsequently often need to know more about the interplay of superconductivity and material prop erties. On the other hand, people working in the field know that a competent and well-written book by S. V. Vonsovsky, V. A. Izyumov, and E. Z. Kurmaev has been available in Russian. It presents a thorough discussion of superconducting transition-metal alloys and compounds. This volume is a translation of an updated version of the Russian edition. The translation was done by A. P. Zavarnitsyn of the authors' institution and by Dr. E. H. Brandt of the Max-Planck-Institut fur Metallforschung in Stuttgart. The master manuscript was ably typed by Mrs. C. Pendl. I would like to take this opportunity to thank each of them. I sincerely hope that the book will turn out to be useful to physicists working in the field of superconductivity as well as to nonspecialists and interested graduate students.

Download or read book Twentieth Annual Report on Materials Research at Stanford University July 1 1980 June 30 1981 written by Stanford University. Center for Materials Research and published by . This book was released on 1981 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Tunneling Spectroscopy Studies of Superconductors written by Basu Dev Oli and published by . This book was released on 2021 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: In multiband superconductors, different bands at the Fermi surface contribute to the superconductivity with different magnitudes of superconducting gaps on different portions of the Fermi surface. Each band in a multiband superconductor has a condensate with an amplitude and phase that weakly interacts with the other bands' condensate. The coupling strength between the bands determines whether one or two superconducting transition temperatures are observed, and it is the key to many peculiar properties. In general, if there are two gaps of different magnitude, there are two different length scales associated with the suppression of these gaps in applied magnetic fields, for example. Therefore, effects of multigap superconductivity can be observed in superconducting vortices, which are twirls of supercurrents that are generated when a superconductor is placed in a magnetic field. Furthermore, the two superconducting order parameters in different bands are characterized by a magnitude and phase. In multiband superconductors, there are collective excitations corresponding to fluctuations of the relative phase of two order parameters, so-called the Leggett mode. The first material identified as multiband superconductor is Magnesium Diboride (MgB2) in 2001 with a critical temperature Tc of 39 K. MgB2 is a superconducting material with the highest transition temperature among all conventional BCS superconductors. It has two superconducting gaps \Delta_\pi ~ 2 meV and \Delta_\sigma\ ~ 7 meV and they arise from the existence of two bands \pi and \sigma bands of boron electrons. The discovery of superconductivity in MgB2 renewed interest in the field of multiband superconductivity. MgB2 has attracted many scientists' attention both for the fundamental importance of understanding the multiband superconductivity and possible applications such as magnets, power cables, bolometers, Josephson junction-based electronic devices, and radio-frequency cavities. Afterward, other materials have been identified as multiband superconductors such as NbSe2, the family of iron-based superconductors, heavy fermion superconductors, multilayer cuprates, borocarbides, etc. This dissertation uses tunneling experiments to highlight multiband superconductivity features in two systems, namely MgB2 thin films and ultrathin films of Pb. Further, we use multiple techniques to study a superconducting material, nitrogen-doped niobium, used for superconducting radio-frequency cavities. For the project on MgB2, MgB2/Native-Oxide/Ag planar junctions are fabricated and characterized down to 2.1 K and in the magnetic field parallel to the sample surface up to 6 Tesla. This work investigates how pairbreaking affects the magnitude and phase of the order parameter in a multiband superconductor. The tunneling spectra are analyzed in the framework of a two-band model developed by our theory collaborator Prof. Alex Gurevich, Old Dominion University. The model allows the extraction of the pair-breaking parameters among other quantities. The analysis shows that the order parameter in the ? band is quickly suppressed in the field, the ? band is cleaner than the ? band. The ratio of pairbreaking parameter in the ? band to the ? band rapidly increases at fields higher than ~0.1 T and then plateau at higher fields. This transition around 0.1 T magnetic field suggests a phase decoupling in the two bands of MgB2. Below the transition, the two bands are phase-locked, so mostly, the superconductivity in the ? band is affected, and after phase decoupling, both bands are affected by the applied field. These results are important for a basic understanding of multiband superconductors and the application implications of this material. This phase decoupling has a new and profound consequence on the superconducting state of a multiband superconductor that has been theoretically predicted and never observed experimentally. For the Pb project, ultrathin films of Pb in ultrahigh vacuum conditions are deposited by e-beam evaporation and characterized with low-temperature scanning tunneling microscopy and spectroscopy (STM/STS). The STM/STS allows measuring the electronic density of states with the highest spatial resolution down to atomic scale. The shape of a superconducting vortex core is determined by the superconducting gap and the Fermi velocity, and the STM allows to map anisotropies of these quantities spatially. The vortex cores of Pb film show a complex shape that evolves from triangular at short distances from the center to a six-fold symmetric star shape farther away from the center. These details are very subtle, and they can be highlighted only if one works within the clean limit (to avoid the averaging effect of the scattering) and by fabricating the heterostructure that pins the vortices spatially. The complex vortex core shape reflects the anisotropy of the two bands that contribute to superconductivity in this material. For the project on Niobium, cold and hot spots from nitrogen-doped Nb cutouts are characterized by low temperature scanning tunneling microscopy and spectroscopy (STM/STS) combined with X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The radiofrequency (RF) measurements of the quality factor and temperature mapping on an N-doped Nb superconducting resonator cavity are carried out at Jefferson Laboratory before cutting out the samples. This work aims to identify possible sources of excess dissipation in hot spots and relate them to the surface chemical composition and superconducting properties. The temperature mapping revealed a strong effect of the cavity cooldown rate on the intensities of hot spots and their spatial distribution, which indicates a significant contribution of trapped vortices to the RF dissipation. SEM images acquired on the cold and hot spots using a secondary electron detector show absence of residual hydride scars and niobium nitrides on their surface. Angle-resolved XPS measurements on the native surface of these samples revealed higher oxidized Nb 3d states on the N-doped Nb cold spots, which is supported by XPS depth profiles done on the samples by Argon ion sputtering. Argon ion sputtering of oxidized Nb removes oxygen preferentially from Nb2O5 and diffuses to bulk, thickening the lower oxidation state layers. The proximity theory framework's tunneling spectra analysis suggests hot spots have stronger pairbreaking due to a weakly reduced pair potential, a thicker metallic suboxide layer, and a wide distribution of the contact resistance. STM imaging of vortex cores shows a triangular vortex lattice in both samples, and the coherence length is nearly the same in hot and cold spots. The experimental data analysis suggests weakly degraded superconducting properties at the surface of hot spot regions are not the primary sources of RF losses. Instead, they are the regions where vortices nucleate first and get trapped during cooling down. These experimental techniques and findings will be crucial in helping to qualify new recipes for SRF cavity production and to boost their performance.

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.