Ginzburg-Landau theory for multiband superconductors: Microscopic derivation

Орлова, Н. В.; Shanenko, A. A.; Miloševıć, M. V.; Peeters, F. M.; Vagov, Alexei; Axt, Vollrath M.

doi:10.1103/physrevb.87.134510

Cited by 74 publications

(80 citation statements)

References 41 publications

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“…It should be mentioned that this quest for new multiband superconductivity is a timely subject due to the possible emergence of nonmonotonic vortex-vortex interactions, a fingerprint of so-called type 1.5 superconductivity. [24][25][26] 174512-1 1098-0121/2013/88(17)/174512 (7) ©2013 American Physical Society…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of lower critical fieldHc1(T)shows nodeless superconductivity in FeSe

et al. 2013

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We investigate the temperature dependence of the lower critical field H c1 (T ) of a high-quality FeSe single crystal under static magnetic fields H parallel to the c axis. The temperature dependence of the first vortex penetration field has been experimentally obtained by two independent methods and the corresponding H c1 (T ) was deduced by taking into account demagnetization factors. A pronounced change in the H c1 (T) curvature is observed, which is attributed to anisotopic s-wave or multiband superconductivity. The London penetration depth λ ab (T ) calculated from the lower critical field does not follow an exponential behavior at low temperatures, as it would be expected for a fully gapped clean s-wave superconductor. Using either a two-band model with s-wave-like gaps of magnitudes 1 = 0.41 ± 0.1 meV and 2 = 3.33 ± 0.25 meV or a single anisotropic s-wave order parameter, the temperature dependence of the lower critical field H c1 (T ) can be well described. These observations clearly show that the superconducting energy gap in FeSe is nodeless.

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Section: Introductionmentioning

confidence: 99%

Temperature dependence of lower critical fieldHc1(T)shows nodeless superconductivity in FeSe

et al. 2013

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“…The presence of Josephson terms in multiband superconductors causes several problems in the Gor'kov type derivations. Recently in a series of papers Vagov and coworkers [12][13][14][15] have made detailed analysis and established a generalisation of the standard GL theory (which is correct to τ 1/2 ) by retaining additional terms in the expansion up to order τ (2n+1)/2 . In practice they have analysed the n = 1 corrections to the order parameter for 1, 2 and 3 bands .…”

Section: Introductionmentioning

confidence: 99%

Beyond the standard model of Ginzburg–Landau theory: multiband superconductors

Wilson¹,

Das²

2014

J. Phys.: Condens. Matter

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The recently discovered multiband superconductors have created a new class of novel superconductors. In these materials multiple superconducting gaps arise due to the formation of Cooper pairs on different sheets of the Fermi surfaces. An important feature of these superconductors is the interband couplings, which not only change the individual gap properties, but also create new collective modes. Here we investigate the effect of the interband couplings in the Ginzburg-Landau theory. We produce a general τ (2n+1)/2 expansion (τ = 1 − T /Tc) and show that this expansion has unexpected behaviour for n ≥ 2. This point emphasises the weaker validity of the GL theory for lower temperatures and gives credence to the existence of hidden criticality near the critical temperature of the uncoupled subdominant band.

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“…12). In addition, dynamic dissociation of vortices is predicted in the flux flow regime [13], as well as the stationary vortex splitting [14,15] stemming from phase frustration in superconductors with three or more bands [16,17], but neither of those vortex fractionalizations has been realized to date.In this Letter we explore the effect of a surface in stabilizing the fractional vortices in multiband superconductors [18], and propose static (dc) and dynamic (ac) measurements to directly detect them. We consider a twoband superconducting slab in parallel magnetic field H, with width much larger than the field penetration depth in order to prevent strong confinement effects.…”

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confidence: 99%

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confidence: 99%

Distinct magnetic signatures of fractional vortex configurations in multiband superconductors

Silva

Milošević

Domı́nguez

et al. 2014

Applied Physics Letters

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Vortices carrying fractions of a flux quantum are predicted to exist in multiband superconductors, where vortex core can split between multiple band-specific components of the superconducting condensate. Using the two-component Ginzburg-Landau model, we examine such vortex configurations in a two-band superconducting slab in parallel magnetic field. The fractional vortices appear due to the band-selective vortex penetration caused by different thresholds for vortex entry within each band-condensate, and stabilize near the edges of the sample. We show that the resulting fractional vortex configurations leave distinct fingerprints in the static measurements of the magnetization, as well as in ac dynamic measurements of the magnetic susceptibility, both of which can be readily used for the detection of these fascinating vortex states in several existing multiband superconductors. PACS numbers: 74.25Ha, 74.25Uv, 74.70Xa, 74.70Ad Multiband superconductors [1, 2] present a variety of intriguing properties that are not found in their singlecomponent counterparts. Theoretical predictions have added more striking properties to that list and challenge experiments to prove them. One of such properties is the appearance of fractional vortices in multiband materials [3], seemingly violating flux quantization. This is only possible for different winding numbers of different order parameters in a system of coexisting weakly interacting condensates, and is facilitated for significantly different length scales of the condensates -especially under mesoscopic confinement [4][5][6][7][8][9]. Weakly coupled multiband materials [10] and superconducting multilayers [11] as their artificial analogue are readily available, hence clever experiments should be devised for detecting and manipulating fractional vortices (see e.g. Ref. 12). In addition, dynamic dissociation of vortices is predicted in the flux flow regime [13], as well as the stationary vortex splitting [14,15] stemming from phase frustration in superconductors with three or more bands [16,17], but neither of those vortex fractionalizations has been realized to date.In this Letter we explore the effect of a surface in stabilizing the fractional vortices in multiband superconductors [18], and propose static (dc) and dynamic (ac) measurements to directly detect them. We consider a twoband superconducting slab in parallel magnetic field H, with width much larger than the field penetration depth in order to prevent strong confinement effects. For our numerical experiments, we have used the two-component Ginzburg-Landau (TCGL) model, where by cautiously setting temperature T close to the critical temperature T c , we ensure the qualitative and quantitative validity of our results (for comparison with other available theoretical models, see e.g. . In the TCGL framework, as given in Ref. 22, eight independent material parameters are needed for a system with both interband and magnetic coupling, namely, the Fermi velocity of the first band v 1 , the square of the ratio of the Ferm...

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Ginzburg-Landau theory for multiband superconductors: Microscopic derivation

Cited by 74 publications

References 41 publications

Temperature dependence of lower critical fieldHc1(T)shows nodeless superconductivity in FeSe

Temperature dependence of lower critical fieldHc1(T)shows nodeless superconductivity in FeSe

Beyond the standard model of Ginzburg–Landau theory: multiband superconductors

Distinct magnetic signatures of fractional vortex configurations in multiband superconductors

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