Unusual boundary effect on coherency of two-band superconductivity

Abstract

We demonstrate that the healing of two-band superconductivity near the surface of the system is governed by length scales which are drastically different from correlation lengths. Similar to the one-band case, one of the characteristic lengths diverges at critical temperature $T_c$, while another one shows unusual behaviour having singularity at $T_{c+}<T_c$. By moving away from the boundary, these scales approach coherence lengths in the bulk state, where the divergence at $T_{c+}$ is removed by arbitrary weak interband coupling. Such a boundary-driven modification in coherency affects proximity phenomenon. We show that critical temperature of binary NS system can exhibit an inflection near $T_{c+}$ as two-band superconducting layer becomes thinner.

8 pages, 5 figures

References in corpus (10)

• Ginzburg-Landau theory of vortices in a multi-gap superconductor
• Microscopic derivation of two-component Ginzburg-Landau model and conditions of its applicability in two-band systems
• Length scales, collective modes, and type-1.5 regimes in three-band superconductors
• Comment on Phys. Rev. B 83, 054515 (2011) by V. G. Kogan and J. Schmalian and comment on their reply Phys. Rev. B 86, 016502 (2012)
• Anomalous proximity effects at the interface of s and s+- superconductors
• Time-reversal symmetry breaking state near the surface of $s_{\pm }$-superconductor
• Critical and non-critical coherence lengths in a two-band superconductor
• Vortex chains due to nonpairwise interactions and field-induced phase transitions between states with different broken symmetry in superconductors with competing order parameters
• Correlations of superconducting fluctuations in a two-gap system
• Two-gap superconductivity: interband interaction in the role of external field