2020/12/31 by Hiroshi Shimahara
Materials Science · Physics and Astronomy · #Condensed matter physics #Electron #Fermi surface #Field (mathematics) #Geometry #Iron-based superconductors research #Magnetic field #Pairing #Pauli exclusion principle #Perpendicular #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Rare-earth and actinide compounds #Superconductivity #cond-mat.supr-con
paper · pdf · doi:10.7566/jpsj.90.044706
published as J. Phys. Soc. Jpn. Vol.90, 044706 (2021) · 7 pages, 2 figures, 3 tables
openalex created_date 2020/12/21 · arxiv created 2021/03/17 · openalex publication_date 2021/03/17 · arxiv updated 2021/03/18 · openalex updated_date 2026/08/05
We examine the Fermi-surface effect called the nesting effect for the FFLO state in strongly Pauli-limited Q2D superconductors, focusing on the effect of 3D factors, such as interlayer electron transfer, interlayer pairing, and off-plane magnetic fields including those perpendicular to the most conductive layers. We examine the systems with a large Maki parameter so that the orbital pair-breaking effect is negligible, except for the locking of the direction of the FFLO vector q in the field direction.It is known that the nesting effect for the FFLO state can be strong in QLD systems in which the orbital pair-breaking effect is suppressed by applying the mag. field parallel to the layers. Hence, it has sometimes been suggested that the nesting effect may hardly enhance the stability of the FFLO state for perpendicular fields. We illustrate that, contrary to this view, the nesting effect can strongly stabilize the FFLO state for perpendicular fields as well as for parallel fields when tz is small so that the Fermi surfaces are open in the kz-direction, where tz denotes the interlayer transfer energy. In particular, the nesting effect in perpendicular fields can be strong in interlayer states. For example, in systems with cylindrical Fermi surfaces warped by tz /= 0, interlayer states with Dltk prop sin kz exhibit mue Hc=1.65 Dlta0 for perpendicular fields, which is much larger than typical values for parallel fields, such as mue Hc=Dlts0 of the s-wave state and mue Hc = 1.28 Deltad0 of the d-wave state in cylindrical systems with tz=0. The present result could potentially provide a physical reason why the areas in the phase diagrams occupied by the high-field phases for the perpendicular and parallel fields are of the same order in CeCoIn5 and FeSe.