Anisotropic criteria for the type of superconductivity

Abstract

The classical criterion for classification of superconductors as type-I or type-II based on the isotropic Ginzburg-Landau theory is generalized to arbitrary temperatures for materials with anisotropic Fermi surfaces and order parameters. We argue that the relevant quantity for this classification is the ratio of the upper and thermodynamic critical fields, $H_{c2}/H_c$, rather than the traditional ratio of the penetration depth and the coherence length, $\lambda /\xi$. Even in the isotropic case, $H_{c2}/H_c$ coincides with $\sqrt{2}\lambda /\xi$ only at the critical temperature $T_c$ and they differ as $T$ decreases, the long known fact. Anisotropies of Fermi surfaces and order parameters may amplify this difference and render false the criterion based on the value of $\kappa =\lambda /\xi$.

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Cited by in corpus (8)

• Niobium in clean limit: an intrinsic type-I superconductor
• Changing the type of superconductivity by magnetic and potential scattering
• Temperature dependence of London penetration depth anisotropy in superconductors with anisotropic order parameters
• Ginzburg-Landau theory of the superheating field anisotropy of layered superconductors
• Enhanced chiral edge currents and orbital magnetic moment in chiral $d$-wave superconductors from mesoscopic finite-size effects
• Fragile superconductivity in a Dirac metal
• Magnetic field at the center of a vortex: a new criterion for the classification of the superconductors
• Designing edge currents using mesoscopic patterning in chiral d-wave superconductors