1,721,106 research outputs found
Anisotropy of Normal and Superconducting State in Fe-based Superconductors
No full textProzorov, Ruslan. (2011). Anisotropy of Normal and Superconducting State in Fe-based Superconductors. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/119026
On the analysis of the tin-inside-H3S Mössbauer experiment
No full textA simple analysis is presented of the particular experiment used to prove the bulk nature of very-high-Tc superconductivity in H3S compound under ultra-high pressure. In the experiment, an internal magnetic field was sensed by the synchrotron Mössbauer spectroscopy in tin placed inside the H3S sample. The experiment showed peculiar anisotropy with respect to the direction of the applied field at first sight. By considering actual experimental geometries and parameters of the experiment, we show that this particular observation is consistent with the expectations for a regular type-II superconductor with Meissner expulsion and pinning.This is a manuscript of an article published as Prozorov, Ruslan, and Sergey L. Bud’ko. "On the analysis of the tin-inside-H3S Mössbauer experiment." Journal of Superconductivity and Novel Magnetism 35, no. 10 (2022): 2615-2619.
DOI: 10.1007/s10948-022-06371-w.
Copyright 2022 The Author(s).
Posted with permission.
DOE Contract Number(s): AC02-07CH11358
Meissner-London Susceptibility of Superconducting Right Circular Cylinders in an Axial Magnetic Field
Full text linkAnalysis of magnetic susceptibility of nonellipsoidal samples is a long-standing problem in experimen-tal studies of magnetism and superconductivity. Here the quantitative description of the Meissner-London response (no Abrikosov vortices) of right circular cylinders in an axial magnetic field is given. Three-dimensional adaptive finite-element modeling is used to calculate the total magnetic moment (m) in a wide range of London penetration depth (lambda) to sample size (a) ratios, lambda/a. By fitting numerical solutions, the closed-form empirical magnetic susceptibility is obtained involving only sample dimensions and lambda, thus providing a recipe for determining the London penetration depth from the precision measurements of the magnetic susceptibility. Detailed protocols of the experimental data analysis using the developed approach are given. The results can be readily extended to the most frequently used cuboid-shaped samples.This article is published as Prozorov, Ruslan. "Meissner-London susceptibility of superconducting right circular cylinders in an axial magnetic field." Physical Review Applied 16, no. 2 (2021): 024014.
DOI: 10.1103/PhysRevApplied.16.024014.
Copyright 2021 American Physical Society.
DOE Contract Number(s): AC02-07CH11358
Niobium in clean limit: an intrinsic type-I superconductor
No full textNiobium is one of the most researched superconductors, both theoretically and experimentally. It is enormously significant in all branches of superconducting applications, from powerful magnets to quantum computing. It is therefore imperative to understand its fundamental properties in great detail. Here, we use the results of recent microscopic calculations of anisotropic electronic, phonon, and superconducting properties, and apply a thermodynamic criterion for the type of superconductivity, more accurate and straightforward than a conventional Ginzburg-Landau parameter κ-based delineation, to show that pure niobium is a type-I superconductor in the clean limit. However, disorder (impurities, defects, strain, stress) pushes it to become a type-II superconductor.This article is published as Prozorov, Ruslan, Mehdi Zarea, and James A. Sauls. "Niobium in the clean limit: An intrinsic type-I superconductor." Physical Review B 106, no. 18 (2022): L180505.
DOI: 10.1103/PhysRevB.106.L180505.
Copyright 2022 American Physical Society.
Posted with permission.
DOE Contract Number(s): AC02-07CH11358; AC02-07CH11359
Contactless measurements of Shubnikov-de Haas oscillations in the magnetically ordered state of CeAgSb2 and SmAgSb2 single crystals
Full text linkShubnikov-de Haas oscillations were measured in single crystals of highly metallic antiferromagnetic SmAgSb2 and ferromagnetic CeAgSb2 using a tunnel diode resonator. Resistivity oscillations as a function of applied magnetic field were observed via measurements of skin depth variation. The effective resolution of Delta rho similar or equal to 20 p Omega allows a detailed study of the SdH spectra as a function of temperature. The effects of the Sm long-range magnetic ordering as well as its electronic structure (4f electrons) on the Fermi surface topology is discussed.This article is published as Prozorov, Ruslan, Matthew D. Vannette, German D. Samolyuk, Stephanie A. Law, Sergey L. Bud’ko, and Paul C. Canfield. "Contactless measurements of Shubnikov-de Haas oscillations in the magnetically ordered state of Ce Ag Sb 2 and Sm Ag Sb 2 single crystals." Physical Review B 75, no. 1 (2007): 014413.
DOI: 10.1103/PhysRevB.75.014413.
Copyright 2007 American Physical Society.
Posted with permission
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Anisotropic superconductivity of niobium based on its response to non-magnetic disorder
Full text linkNiobium is one of the most studied superconductors, both theoretically and
experimentally. It is tremendously important for applications, and it has the
highest superconducting transition temperature, K, of all pure
metals. In addition to power applications in alloys, pure niobium is used for
sensitive magneto-sensing, radio-frequency cavities, and, more recently, as
circuit metallization layers in superconducting qubits. A detailed
understanding of its electronic and superconducting structure, especially its
normal and superconducting state anisotropies, is crucial for mitigating the
loss of quantum coherence in such devices. Recently, a microscopic theory of
the anisotropic properties of niobium with the disorder was put forward. To
verify theoretical predictions, we studied the effect of disorder produced by
3.5 MeV proton irradiation of thin Nb films grown by the same team and using
the same protocols as those used in transmon qubits. By measuring the
superconducting transition temperature and upper critical fields, we show a
clear suppression of by potential (non-magnetic) scattering, which is
directly related to the anisotropic order parameter. We obtain a very close
quantitative agreement between the theory and the experiment
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Linear magnetic susceptibility of anisotropic superconductors of cuboidal shape
Full text linkA simplified model of anisotropic magnetic susceptibility in the Meissner-London vortex-free state of cuboidal superconducting samples is presented. Using this model, precision measurements of the magnetic response in three perpendicular directions of a magnetic field with respect to primary crystal axes, can be used to extract the components of the London penetration depth, thus enabling the evaluation of the general superfluid density tensor, which is needed in the analysis of the superconducting gap structure.Accepted in Journal of Applied Physics: Methods. arXiv admin note: text overlap with arXiv:2101.0648
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