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Giant paramagnetic Meissner effect in multiband superconductors.

da Silva RM, Milošević MV, Shanenko AA, Peeters FM, Aguiar JA - Sci Rep (2015)

Bottom Line: Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux.Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field.We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ciência dos Materiais, Universidade Federal de Pernambuco, Av. Jorn. Aníbal Fernandes, s/n, 50670-901 Recife-PE, Brazil.

ABSTRACT
Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux. In the absence of pinning such paramagnetic response is weak, and ceases with increasing sample thickness. Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field. We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces.

No MeSH data available.


Related in: MedlinePlus

Oblique view of the sample, the superconducting slab of width w, very long in other dimensions (indicated by dashed lines), in parallel magnetic field H.
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f1: Oblique view of the sample, the superconducting slab of width w, very long in other dimensions (indicated by dashed lines), in parallel magnetic field H.

Mentions: We consider a larger than mesoscopic two-band superconducting slab of width w (w/λ ranges from 15 to 50 for the considered parameters) in a parallel magnetic field (see Fig. 1), and report particular behavior of the sample magnetization as a function of the applied field [M(H) loops]. We primarily focus on two-band materials, but our findings can be qualitatively extrapolated to systems with more than two bands. The calculations are performed within the two-component Ginzburg-Landau (TCGL) theory (see Methods), where we have cautiously set a sufficiently high temperature T to ensure the qualitative and quantitative validity of our predictions in the context of recent debates404142434445, and we used full microscopic expressions of all coefficients in the theory444546. TCGL theory then comprises eight independent parameters, namely, the Fermi velocities of the bands v1 and v2, the elements of the coupling matrix λ11, λ22 and λ12 = λ21, the total density of states N(0) as well as the partial density of states of the first band n1 (note n1 + n2 = 1), and finally Tc, which sets the energy scale . By fixing the unit of length ζ1 and normalizing the order parameters by W, the parameters v1 and Tc are fixed, and we are left with six parameters in the model: λ11, λ22, λ12, v1/v2, n1 and N(0). Instead of choosing N(0), we opt to show the GL parameter of the first (stronger) band-condensate , which is an indicator for the expected magnetic behavior of the sample.


Giant paramagnetic Meissner effect in multiband superconductors.

da Silva RM, Milošević MV, Shanenko AA, Peeters FM, Aguiar JA - Sci Rep (2015)

Oblique view of the sample, the superconducting slab of width w, very long in other dimensions (indicated by dashed lines), in parallel magnetic field H.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4525483&req=5

f1: Oblique view of the sample, the superconducting slab of width w, very long in other dimensions (indicated by dashed lines), in parallel magnetic field H.
Mentions: We consider a larger than mesoscopic two-band superconducting slab of width w (w/λ ranges from 15 to 50 for the considered parameters) in a parallel magnetic field (see Fig. 1), and report particular behavior of the sample magnetization as a function of the applied field [M(H) loops]. We primarily focus on two-band materials, but our findings can be qualitatively extrapolated to systems with more than two bands. The calculations are performed within the two-component Ginzburg-Landau (TCGL) theory (see Methods), where we have cautiously set a sufficiently high temperature T to ensure the qualitative and quantitative validity of our predictions in the context of recent debates404142434445, and we used full microscopic expressions of all coefficients in the theory444546. TCGL theory then comprises eight independent parameters, namely, the Fermi velocities of the bands v1 and v2, the elements of the coupling matrix λ11, λ22 and λ12 = λ21, the total density of states N(0) as well as the partial density of states of the first band n1 (note n1 + n2 = 1), and finally Tc, which sets the energy scale . By fixing the unit of length ζ1 and normalizing the order parameters by W, the parameters v1 and Tc are fixed, and we are left with six parameters in the model: λ11, λ22, λ12, v1/v2, n1 and N(0). Instead of choosing N(0), we opt to show the GL parameter of the first (stronger) band-condensate , which is an indicator for the expected magnetic behavior of the sample.

Bottom Line: Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux.Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field.We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces.

View Article: PubMed Central - PubMed

Affiliation: Programa de Pós-Graduação em Ciência dos Materiais, Universidade Federal de Pernambuco, Av. Jorn. Aníbal Fernandes, s/n, 50670-901 Recife-PE, Brazil.

ABSTRACT
Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux. In the absence of pinning such paramagnetic response is weak, and ceases with increasing sample thickness. Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field. We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces.

No MeSH data available.


Related in: MedlinePlus