2003/12/19 by Daniel E. Sheehy, T. P. Davis, Tom P. Davis +2 · 2 citations
Engineering · Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Cuprate #London penetration depth #Mott insulator #Penetration depth #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Quantum tunnelling #Quasiparticle #Superconducting Materials and Applications #Superconductivity #Superfluidity #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.70.054510
published as Phys. Rev. B 70, 054510 (2004) · 13 pages, 8 figures
arxiv created 2003/12/19 · openalex publication_date 2004/08/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We formulate a model describing the doping (x) and temperature (T) dependence of the ab\ensuremath-plane and c-axis penetration depth of a cuprate superconductor. The model incorporates the suppression of the superfluid density with underdoping as the system approaches the Mott-Hubbard insulating state by augmenting a d-wave BCS model with a phenomenological charge renormalization factor that is vanishingly small for states away from the nodes of the d-wave pair potential but close to unity in the vicinity of the nodes. The c-axis penetration depth is captured within a model of incoherent electron tunneling between the CuO2 planes. Application of this model to the recent experimental data on the high-purity single crystals of YBa2Cu3O_6+\ensuremathδ implies existence of a ``nodal protectorate,'' a k-space region in the vicinity of the nodes whose size decreases in proportion to x, in which d-wave quasiparticles remain sharp even as the system teeters on the brink of becoming an insulator. The superfluid density, which is extremely small for these samples, also appears to come exclusively from these protected nodal regions.