Evidence for competition between the superconducting and the pseudogap state in (BiPb)_2(Sr.pdfVIP

a r X i v : 0 8 0 6 .1 9 0 7 v 1 [ c o n d - m a t .s u p r - c o n ] 1 1 J u n 2 0 0 8 PREPRINT (June 11, 2008) Evidence for competition between the superconducting and the pseudogap state in (BiPb)2(SrLa)2CuO6+δ from muon-spin rotation experiments R. Khasanov,1, 2, ? Takeshi Kondo,3, 4 S. Stra?ssle,2 D.O.G. Heron,5 A. Kaminski,3 H. Keller,2 S.L. Lee,5 and Tsunehiro Takeuchi4, 6 1Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 2Physik-Institut der Universita?t Zu?rich, Winterthurerstrasse 190, CH-8057 Zu?rich, Switzerland 3Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, IA 50011, USA 4Department of Crystalline Materials Science, Nagoya University, Nagoya 464-8603, Japan 5School of Physics and Astronomy, University of St. Andrews, Fife, KY16 9SS, UK 6EcoTopia Science Institute, Nagoya University, Nagoya 464-8603, Japan The in-plane magnetic penetration depth λab in optimally doped (BiPb)2(SrLa)2CuO6+δ (OP Bi2201) was studied by means of muon-spin rotation. The measurements of λ?2 ab (T ) are inconsistent with a simple model of a d?wave order parameter and a uniform quasiparticle weight around the Fermi surface. The data are well described assuming the angular gap symmetry obtained in ARPES experiments [Phys. Rev. Lett 98, 267004 (2007)], where it was shown that the superconducting gap in OP Bi2201 exists only in segments of the Fermi surface near the nodes. We find that the remaining parts of the Fermi surface, which are strongly affected by the pseudogap state, do not contribute significantly to the superconducting condensate. Our data provide evidence that high temperature superconductivity and pseudogap behavior in cuprates are competing phenomena. PACS numbers: 74.72.Hs, 74.25.Jb, 76.75.+i The relevance of the pseudogap phenomenon for super- conductivity is an important open issue in the physics of high-temperature cuprate superconductors (HTS’s). There are two main sc