Influence of s± symmetry on unconventional superconductivity in pnictides above the Pauli limit – two-band model study

2013/11/21 by Andrzej Ptok · 1 citation
Materials Science · Mathematics · Physics and Astronomy · #Amplitude #Condensed matter physics #Cooper pair #Electronic band structure #Iron-based superconductors research #Mathematics #Parameter space #Pauli exclusion principle #Phase (matter) #Phase diagram #Physics #Physics of Superconductivity and Magnetism #Position and momentum space #Quantum mechanics #S-wave #Superconductivity #Superconductivity in MgB2 and Alloys #Symmetry (geometry) #cond-mat.str-el #cond-mat.supr-con

paper · pdf · doi:10.1140/epjb/e2013-41007-2

published as Eur. Phys. J. B 87, (2014) 2 · European Physical Journal B (2013)

arxiv created 2013/11/21 · openalex publication_date 2014/01/01 · arxiv updated 2014/10/21 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06

Abstract

The theoretical analysis of the Cooper pair susceptibility shows the two-band Fe-based superconductors (FeSC) to support the existence of the phase with nonzero Cooper pair momentum (called the Fulde-Ferrel-Larkin-Ovchinnikov phase or shortly FFLO), regardless of the order parameter symmetry. Moreover this phase for the FeSC model with s ± symmetry is the ground state of the system near the Pauli limit. This article discusses the phase diagram h-T for FeSC in the two-band model and its physical consequences. We compare the results for the superconducting order parameter with s-wave and s ±-wave symmetry – in first case the FFLO phase can occur in both bands, while in second case only in one band. We analyze the resulting order parameter in real space – showing that the FeSC with s ±-wave symmetry in the Pauli limit have typical properties of one-band systems, such as oscillations of the order parameter in real space with constant amplitude, whereas with s-wave symmetry the oscillations have an amplitude modulation. Discussing the free energy in the superconducting state we show that in absence of orbital effects, the phase transition from the BCS to the FFLO state is always first order, whereas from the FFLO phase to normal state is second order.

Citations

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Cited by

• Unconventional Superconductivity in Iron-Based Superconductors in a Three-Band Model