Multi-Gap Superconductivity on MgB2

Kruchinin, S. P.; Nagao, Hidemi

doi:10.1007/1-4020-3989-1_4

Cited by 3 publications

(3 citation statements)

References 19 publications

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“…It has been fitted with an asymmetric Lorentzian with Fano line-shape [8] centred at z=0, with the half width /2=300 meV and an asymmetry parameter q=4. This experimental curve provides the clear experimental evidence for the T c enhancement driven by interband pairing shows a resonance centred at z=0, as expected for Feshbach shape resonanceIn conclusion we have discussed the Feshbach shape resonances around a type (I), type (II) and type (III) ETT in heterostructures and in the particular case of MgB 2 where the two band scenario is well established [205][206][207], we have shown that the Feshbach shape resonance in interband pairing occurs in a superlattice of superconducting layers near a type (II) ETT in this particular multiband superconductor in the clean limit. The Feshbach shape resonance increases the critical temperature from low T c diborides up to T c =40K in MgB 2 and it provides the most clear case of T c amplification beyond the limit of 20K.…”

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confidence: 63%

Feshbach Shape Resonances in Multiband High Tc Superconductors

Bianconi

Filippi

Symmetry and Heterogeneity in High Temperature Superconductors

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Abstract:We describe particular nanoarchitectures (superlattices of superconducting wires and layers) where a mechanism to evade temperature decoherence effects in a quantum condensate is switched on by tuning the charge density. The superlattice structure determines the subbands and the corresponding Bloch wavefunctions of charge carriers at the Fermi level with different parity and different spatial locations. The disparity and negligible overlap between electron wave-functions in different subbands suppress the single electron interband impurity scattering rate and allow the multiband superconductivity in the clean limit. The quantum trick that bestows to the system the property to resist to the decoherence attacks of high temperature is the Feshbach shape resonance in the interband off-diagonal exchange-like pairing term i.e., in the quantum configuration interaction between pairing channels in different subbands. It occurs by tuning the chemical potential at a particular point near a Van Hove singularity (vHs) in the electronic energy spectrum, or a Lifshitz electronic topological transition (ETT), associated with the change of the dimensionality of the Fermi surface topology of one of the subbands.

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confidence: 63%

Feshbach Shape Resonances in Multiband High Tc Superconductors

Bianconi

Filippi

Symmetry and Heterogeneity in High Temperature Superconductors

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“…Many publications have been devoted to the investigation of the various properties of MgB 2 superconductors and their theoretical considerations (e.g., [ 19 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 ] and the references therein). MgB 2 ’s properties are considered more similar to metal than to those of HTS [ 28 ].…”

Section: Introductionmentioning

confidence: 99%

“…The theoretical understanding of the properties of MgB 2 superconductors has nearly been achieved by the consideration of two energy gaps. The measured and estimated gaps of the π- and σ-bands of the electrons of MgB 2 are typically around 2 meV and 6.5 meV, respectively [ 29 , 34 , 35 , 38 , 39 ]. In [ 39 ], it was noted, that these gaps can vary in the ranges of 1–4 meV and 5.5–10 meV.…”

Section: Introductionmentioning

confidence: 99%

Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications

Prikhna,

Sokolovsky,

Moshchil

2024

Materials

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The intensive development of hydrogen technologies has made very promising applications of one of the cheapest and easily produced bulk MgB2-based superconductors. These materials are capable of operating effectively at liquid hydrogen temperatures (around 20 K) and are used as elements in various devices, such as magnets, magnetic bearings, fault current limiters, electrical motors, and generators. These applications require mechanically and chemically stable materials with high superconducting characteristics. This review considers the results of superconducting and structural property studies of MgB2-based bulk materials prepared under different pressure–temperature conditions using different promising methods: hot pressing (30 MPa), spark plasma sintering (16–96 MPa), and high quasi-hydrostatic pressures (2 GPa). Much attention has been paid to the study of the correlation between the manufacturing pressure–temperature conditions and superconducting characteristics. The influence of the amount and distribution of oxygen impurity and an excess of boron on superconducting characteristics is analyzed. The dependence of superconducting characteristics on the various additions and changes in material structure caused by these additions are discussed. It is shown that different production conditions and additions improve the superconducting MgB2 bulk properties for various ranges of temperature and magnetic fields, and the optimal technology may be selected according to the application requirements. We briefly discuss the possible applications of MgB2 superconductors in devices, such as fault current limiters and electric machines.

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Multiband Model of Cuprate Superconductivity

Kristoffel

Rubin

Örd

2008

Int. J. Mod. Phys. B

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A minimal model for the description of cuprate superconductor characteristics on doping scale (hole and electron) is developed. The leading interband pairing channel couples an itinerant band and defect states created by doping. Bare gaps between them are supposed and become closed by extended doping. Band overlap conditions determine special points in the phase diagram. Nodal and antinodal momentum regions are distinguished. Illustrative calculations have been made using a mean-field pair-transfer multiband Hamiltonian and corresponding free-energy expansions. The results are self-consistent and demonstrate that the elaborated approach is able to reproduce characteristic features of cuprate superconductors as, e.g., the doping dependence of Tc, superconducting gaps and pseudogaps, supercarrier density and effective mass, coherence length and penetration depth, critical magnetic fields and some other properties. Interband pairing scheme is suggested to be an essential aspect of cuprate superconductivity.

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Multi-Gap Superconductivity on MgB2

Cited by 3 publications

References 19 publications

Feshbach Shape Resonances in Multiband High Tc Superconductors

Feshbach Shape Resonances in Multiband High Tc Superconductors

Bulk MgB2 Superconducting Materials: Technology, Properties, and Applications

Multiband Model of Cuprate Superconductivity

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