1999/12/31 by Andrea Perali, A. Perali, C. Castellani +5 · 1 citation
Engineering · Physics and Astronomy · #Physics of Superconductivity and Magnetism #Superconducting Materials and Applications #Superconductivity in MgB2 and Alloys #cond-mat.str-el #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.62.r9295
5 pages, 1 enclosed figure. For further information see http://htcs.org
arxiv created 2000/05/11 · openalex publication_date 2000/10/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Various properties of underdoped superconducting cuprates, including the momentum-dependent pseudogap opening, indicate a behavior which is neither BCS- nor Bose-Einstein condensation (BEC)-- like. To explain this issue we introduce a two-gap model. This model assumes an anisotropic pairing interaction among two kinds of fermions with small and large Fermi velocities representing the quasiparticles near the M and the nodal points of the Fermi surface, respectively. We find that a gap forms near the M points resulting in incoherent pairing due to strong fluctuations. Instead, the pairing near the nodal points sets in with phase coherence at lower temperature. By tuning the momentum-dependent interaction, the model allows for a continuous evolution from a pure BCS pairing (in the overdoped and optimally doped regime) to a mixed boson-fermion picture (in the strongly underdoped regime).