Magnetic field dependence of the coherence length and penetration depth of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>MgB</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>single crystals

Klein, Thierry; Lyard, L.; Marcus, J.; Hoľanová, Z.; Marcenat, C.

doi:10.1103/physrevb.73.184513

Cited by 34 publications

(61 citation statements)

References 40 publications

(36 reference statements)

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“…In a µSR study of NbSe 2 at T = 0.02 K, in which thermal excitations of the bound quasiparticle core states are largely frozen out, Callaghan et al This is consistent with the full field dependence of the core size inferred from specific heat measurements [109].…”

Section: And Nb: Marginal Type-ii Superconductorssupporting

confidence: 65%

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Sonier

2007

Rep. Prog. Phys.

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The focus of this article is on recent progress in muon spin rotation (µSR) studies of the vortex cores in type-II superconductors. By comparison of µSR measurements of the vortex-core size in a variety of materials with results from techniques that directly probe electronic states, the effect of delocalized quasiparticles on the spatial variation of field in a lattice of interacting vortices has been determined for both single-band and multi-band superconductors. These studies demonstrate the remarkable accuracy of what some still consider an exotic technique. In recent years µSR has also been used to search for magnetism in and around the vortex cores of high-temperature superconductors. As a local probe µSR is specially suited for detecting static or quasistatic magnetism having short-range or random spatial correlations. As discussed in this review, µSR experiments support a generic phase diagram of competing superconducting and magnetic order parameters, characterized by a quantum phase transition to a state where the competing order is spatially non-uniform.

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Section: And Nb: Marginal Type-ii Superconductorssupporting

confidence: 65%

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Sonier

2007

Rep. Prog. Phys.

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“…Such a nonlinearity cannot be described by a single-gap isotropic s-wave model even if the delocalized quasiparticles are taken into account [7]. The observed cðHÞ behavior more resembles that of MgB 2 [8] the spectacular example of the two-gap superconductivity. We add that specific heat data of the presented type could be eventually explained also by the anisotropic s-wave superconductivity but this would be incompatible with the measurements by STM/S [2].…”

Section: Resultsmentioning

confidence: 74%

Studies on two-gap superconductivity in 2H–NbS2

Kačmarčı́k

Marcenat

Klein

et al. 2010

Physica C: Superconductivity and its Applications

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“…For an s-wave superconductor a linear-field dependence ␥͑H͒ ϰ H is expected, 52,53 while for a nodal gap, ␥͑H͒ ϰ H 1/2 . 54,55 The data from several groups vary in the details, 46,47,[56][57][58] but in all cases at low fields the data follow ␥͑H͒ ϰ H n with 0 Ͻ n Ͻ 1. Clear low-temperature low-field dependence ␥͑H͒ ϰ H 1/2 is reported in recent single-crystal experiments [56][57][58] which is in direct support of the proposed -gap symmetry of Eq.…”

Section: Relation Of Our Findings To Existing Literaturementioning

confidence: 99%

Evidence for non-s-wave symmetry of theπgap inMgB2from intermodulation distortion measurements

Agassi

Oates

Moeckly³

2009

Phys. Rev. B

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We present low-temperature low-power intermodulation-distortion ͑IMD͒ measurements of high-quality MgB 2 thin films that are inconsistent with presumed s-wave symmetry of the order parameter. The measurements were carried out in a stripline resonator at approximately 2 GHz between 1.8 K and T c . The IMD arises from the nonlinear Meissner effect in which the penetration depth is dependent on the RF magnetic field. Specifically, the observed IMD vs temperature T for T Ӷ T c / 2 varies as T −2 , while for an s-wave gap symmetry in the clean limit, the low-temperature IMD decreases exponentially with decreasing temperature. We calculate the IMD from first principles for different order-parameter symmetries using a Green's function approach and compare the results with the measured data. We propose that the observed upturn in the low-temperature IMD implies an admixture of an order parameter with nodal lines into the energy gaps of MgB 2 . Most likely, this admixture is prominent for the gap. Within the constraints of the hexagonal crystal symmetry of MgB 2 , the best fit with our IMD measurements is obtained with a gap ⌬͑ , T͒ = ⌬ 0 ͑T͒sin͑6͒, where is the azimuthal angle in the ab plane, and ⌬ 0 ͑T͒ is the amplitude, weakly temperature dependent at low temperatures. This gap symmetry entails six nodal lines. We also present low-temperature penetration-depth measurements that are consistent with the proposed nodal gap symmetry. To relate our proposition with existing literature, we review other low-temperature probes of the order-parameter symmetry. The literature presents conflicting results, some of which are in direct support of the symmetry proposed here.

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Magnetic field dependence of the coherence length and penetration depth ofMgB2single crystals

Cited by 34 publications

References 40 publications

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Muon spin rotation studies of electronic excitations and magnetism in the vortex cores of superconductors

Studies on two-gap superconductivity in 2H–NbS2

Evidence for non-s-wave symmetry of theπgap inMgB2from intermodulation distortion measurements

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