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Chen Y, Shanenko AA. Multiband Superconductors: Two Characteristic Lengths for Each Contributing Condensate. J Phys Chem Lett 2022; 13:10350-10355. [PMID: 36314666 DOI: 10.1021/acs.jpclett.2c02867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The interference of multiple condensates coexisting in one system may lead to unconventional coherent behavior. This is expected when the spatial lengths of the condensates are essentially different. Traditionally, the characteristic spatial length of a superconducting condensate is associated with the gap function. However, the broader readership is more familiar with the concept of the Cooper-pair wave function. For conventional single-band superconductors, the gap function coincides with the center-of-mass Cooper-pair wave function up to the coupling constant, and the corresponding gap and wave function characteristic lengths are the same. Surprisingly, we find that in two-band superconductors, these lengths are the same only near the critical temperature. At lower temperatures, they can significantly deviate from each other, and the fundamental question of which of these lengths should be preferred when specifying the spatial scale of a band-dependent condensate in multiband superconducting materials arises.
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Affiliation(s)
- Yajiang Chen
- Key Laboratory of Optical Field Manipulation of Zhejiang Province, Department of Physics, Zhejiang Sci-Tech University, Hangzhou310018, China
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2
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Datta S, Vasdev A, Halder S, Singh J, Singh Y, Sheet G. Spectroscopic signature of two superconducting gaps and their unusual field dependence in RuB 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:315701. [PMID: 32097894 DOI: 10.1088/1361-648x/ab79f6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Accepted: 02/25/2020] [Indexed: 06/10/2023]
Abstract
Recently RuB2was shown to be a possible two-gap, type-I superconductor. Temperature dependent heat capacity measurements revealed a two-gap superconducting ground state, while magnetic field dependent magnetization measurements indicated surprizing type-I superconductivity with a very low experimental critical field (Hc) ∼120 Oe. In this paper, we report direct spectroscopic evidence of two superconducting energy gaps in RuB2. We have measured scanning tunnelling spectra exhibiting signature of two gaps on different grains of polycrystalline RuB2, possibly originating from multiple bands. Analysis of the temperature dependent tunnelling spectra revealed that the gaps from different bands evolve differently with temperature before disappearing simultaneously at a singleTc. Interestingly, our experiments also reveal that the gaps in quasiparticle density of states survive up to magnetic fields much higher than the bulkHcand they evolve smoothly with field, unlike what is expected for a type-I superconductor, indicating the existence of a 'mixed state'.
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Affiliation(s)
- Soumya Datta
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
| | - Aastha Vasdev
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
| | - Soumyadip Halder
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
| | - Jaskaran Singh
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
| | - Yogesh Singh
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
| | - Goutam Sheet
- Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, Mohali 140306, India
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3
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Enhancement of superconductivity under pressure and the magnetic phase diagram of tantalum disulfide single crystals. Sci Rep 2016; 6:31824. [PMID: 27534898 PMCID: PMC4989151 DOI: 10.1038/srep31824] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 07/27/2016] [Indexed: 11/17/2022] Open
Abstract
In low-dimensional electron systems, charge density waves (CDW) and superconductivity are two of the most fundamental collective quantum phenomena. For all known quasi-two-dimensional superconductors, the origin and exact boundary of the electronic orderings and superconductivity are still attractive problems. Through transport and thermodynamic measurements, we report on the field-temperature phase diagram in 2H-TaS2 single crystals. We show that the superconducting transition temperature (Tc) increases by one order of magnitude from temperatures at 0.98 K up to 9.15 K at 8.7 GPa when the Tc becomes very sharp. Additionally, the effects of 8.7 GPa illustrate a suppression of the CDW ground state, with critically small Fermi surfaces. Below the Tc the lattice of magnetic flux lines melts from a solid-like state to a broad vortex liquid phase region. Our measurements indicate an unconventional s-wave-like picture with two energy gaps evidencing its multi-band nature.
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4
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Multiband Semimetallic Electronic Structure of Superconducting Ta2PdSe5. PLoS One 2015; 10:e0123667. [PMID: 25909894 PMCID: PMC4409351 DOI: 10.1371/journal.pone.0123667] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/20/2015] [Indexed: 11/19/2022] Open
Abstract
We report the electronic structure and related properties of the superconductor Ta2PdSe5 as determined from density functional calculations. The Fermi surface has two disconnected sheets, both derived from bands of primarily chalcogenide p states. These are a corrugated hole cylinder and a heavier complex shaped electron sheet. The sheets contain 0.048 holes and a compensating number of electrons per formula unit, making the material a semimetallic superconductor. The results support the presence of two band superconductivity, although a discrepancy in the specific heat is noted. This discrepancy is discussed as a possible consequence of Pd deficiency in samples.
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5
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Putzke C, Walmsley P, Fletcher JD, Malone L, Vignolles D, Proust C, Badoux S, See P, Beere HE, Ritchie DA, Kasahara S, Mizukami Y, Shibauchi T, Matsuda Y, Carrington A. Anomalous critical fields in quantum critical superconductors. Nat Commun 2014; 5:5679. [PMID: 25477044 PMCID: PMC4268691 DOI: 10.1038/ncomms6679] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 10/28/2014] [Indexed: 11/22/2022] Open
Abstract
Fluctuations around an antiferromagnetic quantum critical point (QCP) are believed to lead to unconventional superconductivity and in some cases to high-temperature superconductivity. However, the exact mechanism by which this occurs remains poorly understood. The iron-pnictide superconductor BaFe2(As1−xPx)2 is perhaps the clearest example to date of a high-temperature quantum critical superconductor, and so it is a particularly suitable system to study how the quantum critical fluctuations affect the superconducting state. Here we show that the proximity of the QCP yields unexpected anomalies in the superconducting critical fields. We find that both the lower and upper critical fields do not follow the behaviour, predicted by conventional theory, resulting from the observed mass enhancement near the QCP. Our results imply that the energy of superconducting vortices is enhanced, possibly due to a microscopic mixing of antiferromagnetism and superconductivity, suggesting that a highly unusual vortex state is realized in quantum critical superconductors. Superconductivity in the iron pnictides is believed to be related to quantum critical fluctuations. Putzke et al. observe unexpected anomalies in the critical fields of BaFe2(As1−xPx)2 that emerge close to its magnetic critical point, which they argue is a generic feature of quantum critical superconductivity.
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Affiliation(s)
- C Putzke
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - P Walmsley
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - J D Fletcher
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - L Malone
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
| | - D Vignolles
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - C Proust
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - S Badoux
- Laboratoire National des Champs Magnétiques Intenses (CNRS-INSA-UJF-UPS), 31400 Toulouse, France
| | - P See
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, UK
| | - H E Beere
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - D A Ritchie
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE, UK
| | - S Kasahara
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - Y Mizukami
- 1] Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan [2] Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - T Shibauchi
- 1] Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan [2] Department of Advanced Materials Science, University of Tokyo, Kashiwa 277-8561, Japan
| | - Y Matsuda
- Department of Physics, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
| | - A Carrington
- H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, UK
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6
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Size dependent structural, electronic, and magnetic properties of Sc(N) (N=2-14) clusters investigated by density functional theory. J Mol Model 2014; 20:2481. [PMID: 25337684 DOI: 10.1007/s00894-014-2481-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 09/28/2014] [Indexed: 10/24/2022]
Abstract
Structural, electronic, and magnetic properties of ScN (N=2-14) clusters have been investigated using density functional theory (DFT) calculations. Different spin states isomer for each cluster size has been optimized with symmetry relaxation. The structural stability, dissociation energy, binding energy, spin stability, vertical ionization energy, electron affinity, chemical hardness, and size dependent magnetic moment per atom are calculated for the energetically most stable spin isomer for each size. The structural stability for a specific size cluster has been explained in terms of atomic shell closing effect, close packed symmetric structure, and chemical bonding. Spin stability of each cluster size is determined by calculating the value of spin gaps. The maximum value for second-order energy difference is observed for the clusters of size N = 2, 6, 11, and 13, which implies that these clusters are relatively more stable. The magnetic moment per atom corresponding to lowest energy structure has also been calculated. The magnetic moment per atom corresponding to lowest energy structures has been calculated. The calculated values of magnetic moment per atom vary in an oscillatory fashion with cluster size. The calculated results are compared with the available experimental data.
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Kopnin NB, Khaymovich IM, Mel'nikov AS. Predicted multiple cores of a magnetic vortex threading a two-dimensional metal proximity coupled to a superconductor. PHYSICAL REVIEW LETTERS 2013; 110:027003. [PMID: 23383934 DOI: 10.1103/physrevlett.110.027003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Indexed: 06/01/2023]
Abstract
The structure of a proximity induced vortex core in a two-dimensional metallic layer covering a superconducting half-space is calculated. We predict the formation of a multiple vortex core characterized by two-scale behavior of the local density of states. For coherent tunneling between the two-dimensional layer and the bulk superconductor, the spectrum has two subgap branches while for incoherent tunneling only one of them remains. The resulting splitting of the zero-bias anomaly and the multiple peak structure in the local density of states should be visible in the tunneling spectroscopy experiments.
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Affiliation(s)
- N B Kopnin
- O. V. Lounasmaa Laboratory, Aalto University, P.O. Box 15100, 00076 Aalto, Finland
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Chen Y, Shanenko AA, Perali A, Peeters FM. Superconducting nanofilms: molecule-like pairing induced by quantum confinement. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:185701. [PMID: 22481115 DOI: 10.1088/0953-8984/24/18/185701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Quantum confinement of the perpendicular motion of electrons in single-crystalline metallic superconducting nanofilms splits the conduction band into a series of single-electron subbands. A distinctive feature of such a nanoscale multi-band superconductor is that the energetic position of each subband can vary significantly with changing nanofilm thickness, substrate material, protective cover and other details of the fabrication process. It can occur that the bottom of one of the available subbands is situated in the vicinity of the Fermi level. We demonstrate that the character of the superconducting pairing in such a subband changes dramatically and exhibits a clear molecule-like trend, which is very similar to the well-known crossover from the Bardeen-Cooper-Schrieffer regime to Bose-Einstein condensation (BCS-BEC) observed in trapped ultracold fermions. For Pb nanofilms with thicknesses of 4 and 5 monolayers (MLs) this will lead to a spectacular scenario: up to half of all the Cooper pairs nearly collapse, shrinking in the lateral size (parallel to the nanofilm) down to a few nanometers. As a result, the superconducting condensate will be a coherent mixture of almost molecule-like fermionic pairs with ordinary, extended Cooper pairs.
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Affiliation(s)
- Yajiang Chen
- Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium
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Machida Y, Sakai S, Izawa K, Okuyama H, Watanabe T. Enhanced quasiparticle heat conduction in the multigap superconductor Lu2Fe3Si5 . PHYSICAL REVIEW LETTERS 2011; 106:107002. [PMID: 21469825 DOI: 10.1103/physrevlett.106.107002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Indexed: 05/30/2023]
Abstract
Thermal transport measurements have been made on the Fe-based superconductor Lu2Fe3Si5 (T(c) ∼ 6 K) down to a very low temperature T(c)/120. The field and temperature dependences of the thermal conductivity confirm the multigap superconductivity with fully opened gaps on the whole Fermi surfaces. In comparison to MgB2, Lu2Fe3Si5 reveals a remarkably enhanced quasiparticle heat conduction in the mixed state. The results can be interpreted as a consequence of the unequal weight of the Fe 3d-electron character among the distinct bands.
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Affiliation(s)
- Y Machida
- Department of Physics, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
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10
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Karmakar M, Dey B. Effect of two length scales on the properties of MgB(2) for arbitrary applied magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:205701. [PMID: 21393710 DOI: 10.1088/0953-8984/22/20/205701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Experiments carried out on the intermetallic superconducting material MgB(2) have shown anomalous magnetic field dependence of upper critical field, small angle neutron scattering form factor, specific heat, critical current etc. Similarly, scanning tunnelling microscopy (STM) experiments on vortex structures have shown unusually large vortex core size and two different magnetic and spatial field scales. Also, whereas the specific heat measurements and isotope shift experiments have shown Bardeen-Cooper-Schrieffer-like (BCS-like) behaviour, the temperature dependences of the penetration depth experiments have shown non-BCS-like behaviour. These anomalous behaviours have been attributed to the multiband superconductivity of this material and the nature of the local spatial behaviour of the magnetic induction and the order parameter components having two length scales. We report an analytical investigation of the effect of two length scales on the temperature and the applied magnetic field dependence of several properties of MgB(2), such as, the penetration depth, single vortex and vortex lattice structure, vortex core radius, reversible magnetization, critical current, small angle neutron scattering form factor and the shear modulus of the vortex lattice within the framework of two-order parameter Ginzburg-Landau theory. We solve the corresponding nonlinear Ginzburg-Landau equations numerically exactly using an iterative method for arbitrary applied field H(c1) < H < H(c2), the Ginzburg-Landau parameter and vortex lattice symmetry. This enables us to compute the local spatial behaviour of the magnetic induction and the order parameters accurately for arbitrary applied field and a wide range of temperature. Comparison of the analytical results with experiments on MgB(2) gives very good agreement.
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Park MS, Lee HS, Kim JD, Kim HJ, Jung MH, Jo Y, Lee SI. Analysis of H(c2)(θ,T) for Mg(B(1-x)C(x))(2) single crystals by using the dirty two-gap model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:242201. [PMID: 21694031 DOI: 10.1088/0953-8984/19/24/242201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
To understand the effect of carbon doping on the superconductivity in MgB(2), we obtained the angle- and temperature-dependent upper critical fields [H(c2)(θ) and H(c2)(T)] for Mg(B(1-x)C(x))(2) single crystals (x = 0.06 and 0.1) from resistivity measurements while varying the temperature, the field, and the direction of the field. The detailed values of the diffusivity for two different directions for each σ-band and π-band were obtained to explain both the temperature- and the angle-dependent H(c2) by using the dirty-limit two-gap model. The induced impurity scattering of the σ-band and the π-band for both the ab-plane and the c-direction is studied.
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Affiliation(s)
- Min-Seok Park
- National Creative Research Initiative Center for Superconductivity and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea
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12
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Pribulova Z, Klein T, Marcus J, Marcenat C, Levy F, Park MS, Lee HG, Kang BW, Lee SI, Tajima S, Lee S. Anisotropy of the Sommerfeld coefficient in magnesium diboride single crystals. PHYSICAL REVIEW LETTERS 2007; 98:137001. [PMID: 17501231 DOI: 10.1103/physrevlett.98.137001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2006] [Indexed: 05/15/2023]
Abstract
The anisotropic field dependence of the Sommerfeld coefficient gamma has been measured down to B-->0 by combining specific heat and Hall probe magnetization measurements in MgB2 single crystals. We find that gamma(B,theta) is the sum of two contributions arising from the sigma and pi band, respectively. We show that gammasigma(B,theta)=B/Bc2(theta) where Bc2(theta)=Bc2ab/sqrt[sin2theta+Gamma2cos2theta] with Gamma approximately 5.4 (theta being the angle between the applied field and the c axis) and gammapi(B,theta)=gammapi(B)=B/Bpi(B). The "critical field" of the pi band Bpi is fully isotropic but field dependent increasing from approximately 0.25 T for B< or =0.1 T up to 3 T approximately Bc2c for B-->3 T. Because of the coupling of the two bands, superconductivity survives in the pi band up to 3 T but is totally destroyed above for any orientation of the field.
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Affiliation(s)
- Z Pribulova
- Institut Néel-CNRS, F-38042 Grenoble Cedex 9, France
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Bao XY, Zhang YF, Wang Y, Jia JF, Xue QK, Xie XC, Zhao ZX. Quantum size effects on the perpendicular upper critical field in ultrathin lead films. PHYSICAL REVIEW LETTERS 2005; 95:247005. [PMID: 16384412 DOI: 10.1103/physrevlett.95.247005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Indexed: 05/05/2023]
Abstract
We report the thickness-dependent (in terms of atomic layers) oscillation behavior of the perpendicular upper critical field Hc2perpendicular in the ultrathin lead films at the reduced temperature (t = T/Tc). Distinct oscillations of the normal-state resistivity as a function of film thickness have also been observed. Compared with the Tc oscillation, the Hc2perpendicular shows a considerable large oscillation amplitude and a pi phase shift. The oscillatory mean free path caused by the quantum size effect plays a role in Hc2perpendicular oscillation.
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Affiliation(s)
- Xin-Yu Bao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China
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14
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Gorokhov DA. Surface superconductivity of dirty two-band superconductors: applications to MgB2. PHYSICAL REVIEW LETTERS 2005; 94:077004. [PMID: 15783845 DOI: 10.1103/physrevlett.94.077004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Indexed: 05/24/2023]
Abstract
The minimal magnetic field H(c2) destroying superconductivity in the bulk of a superconductor is smaller than the magnetic field H(c3) needed to destroy surface superconductivity if the surface of a superconductor coincides with one of the crystallographic planes and is parallel to the external magnetic field. While for a dirty single-band superconductor the ratio of H(c3) to H(c2) is a universal temperature-independent constant 1.6946, for dirty two-band superconductors this is not the case. I show that in the latter case the interaction of the two bands leads to a novel scenario with the ratio H(c3)/H(c2) varying with temperature and taking values larger and smaller than 1.6946. The results are applied to MgB(2) and compared with recent experiments (A. Rydh, cond-mat/0307445).
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Affiliation(s)
- Denis A Gorokhov
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853-2501, USA
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15
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Serventi S, Allodi G, De Renzi R, Guidi G, Romanò L, Manfrinetti P, Palenzona A, Niedermayer C, Amato A, Baines C. Effect of two gaps on the flux-lattice internal field distribution: evidence of two length scales in Mg(1-x)AlxB2 from muSR. PHYSICAL REVIEW LETTERS 2004; 93:217003. [PMID: 15601053 DOI: 10.1103/physrevlett.93.217003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Indexed: 05/24/2023]
Abstract
We have measured the transverse field muon spin precession in the flux-lattice (FL) state of the two-gap superconductor MgB2 and of the electron doped compounds Mg(1-x)AlxB2 in magnetic fields up to 2.8 T. We show the effect of the two gaps on the internal field distribution in the FL, from which we determine two coherence length parameters and the doping dependence of the London penetration depth. This is an independent determination of the complex vortex structure already suggested by the STM observation of large vortices in a MgB2 single crystal. Our data agree quantitatively with STM and we thus validate a new phenomenological model for the internal fields.
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Affiliation(s)
- S Serventi
- Dipartimento di Fisica e Unità, INFM di Parma, I 43100 Parma, Italy
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16
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Koshelev AE, Golubov AA. Why magnesium diboride is not described by anisotropic Ginzburg-Landau theory. PHYSICAL REVIEW LETTERS 2004; 92:107008. [PMID: 15089235 DOI: 10.1103/physrevlett.92.107008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2003] [Indexed: 05/24/2023]
Abstract
It is well established that the superconductivity in the recently discovered superconducting compound MgB2 resides in the quasi-two-dimensional band (sigma band) and three-dimensional band (pi band). We demonstrate that, due to such band structure, the anisotropic Ginzburg-Landau theory practically does not have a region of applicability, because gradient expansion in the c direction breaks down. In the case of a dirty pi band, we derive the simplest equations, which describe properties of such superconductors near Tc, and explore some consequences of these equations.
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Affiliation(s)
- A E Koshelev
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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