Upper critical field in dirty two-band superconductors: Breakdown of the anisotropic Ginzburg-Landau theory
- 4 September 2003
- journal article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 68 (10)
- https://doi.org/10.1103/physrevb.68.104503
Abstract
We investigate the upper critical field in a dirty two-band superconductor within quasiclassical Usadel equations. The regime of very high anisotropy in the quasi-2D band, relevant for MgB$_{2}$, is considered. We show that strong disparities in pairing interactions and diffusion constant anisotropies for two bands influence the in-plane $H_{c2}$ in a different way at high and low temperatures. This causes temperature-dependent $H_{c2}$ anisotropy, in accordance with recent experimental data in MgB$_{2}$. The three-dimensional band most strongly influences the in-plane $H_{c2}$ near $T_{c}$, in the Ginzburg-Landau (GL) region. However, due to a very large difference between the c-axis coherence lengths in the two bands, the GL theory is applicable only in an extremely narrow temperature range near $T_c$. The angular dependence of $H_{c2}$ deviates from a simple effective-mass law even near $T_c$.Comment: 12 pages, 5 figures, submitted to Phys.Rev.
Keywords
This publication has 37 references indexed in Scilit:
- The origin of the anomalous superconducting properties of MgB2Nature, 2002
- First-principles calculation of the superconducting transition inwithin the anisotropic Eliashberg formalismPhysical Review B, 2002
- Beyond Eliashberg Superconductivity in: Anharmonicity, Two-Phonon Scattering, and Multiple GapsPhysical Review Letters, 2001
- Giant Anharmonicity and Nonlinear Electron-Phonon Coupling in: A Combined First-Principles Calculation and Neutron Scattering StudyPhysical Review Letters, 2001
- Electron-phonon interaction in the normal and superconducting states ofPhysical Review B, 2001
- Superconductivity of Metallic Boron inPhysical Review Letters, 2001
- Superconductivity of: Covalent Bonds Driven MetallicPhysical Review Letters, 2001
- Superconductivity at 39 K in magnesium diborideNature, 2001
- Modification of the Upper Critical Field in a Two-Band SuperconductorPhysical Review Letters, 1967
- Bardeen-Cooper-Schrieffer Theory of Superconductivity in the Case of Overlapping BandsPhysical Review Letters, 1959