Phase-fluctuating superconductivity in overdoped La2−xSrxCuO4

Nature Physics - Tập 7 - Trang 455-458 - 2011
Patrick M. C. Rourke1, Ioanna Mouzopoulou1, Xiaofeng Xu2,3, Christos Panagopoulos2,4, Yue Wang5, Baptiste Vignolle6, Cyril Proust6, Evgenia V. Kurganova7, Uli Zeitler7, Yoichi Tanabe8, Tadashi Adachi8, Yoji Koike8, Nigel E. Hussey1
1H.H. Wills Physics Laboratory, University of Bristol, Bristol BS8 1TL, UK
2Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 Singapore, Singapore
3Department of Physics, Hangzhou Normal University, Hangzhou 310036, China
4Department of Physics, University of Crete, and FORTH, 71003 Heraklion, Greece
5State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871, China
6Laboratoire National des Champs Magnetiques Intenses (CNRS, INSA, UJF, UPS), Toulouse 31400, France
7High Field Magnet Laboratory, Institute for Molecules and Materials, Radboud University Nijmegen, 6525 ED Nijmegen, The Netherlands
8Department of Applied Physics, Graduate School of Engineering, Tohoku University, 6-6-05 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

Tóm tắt

Superconducting phase fluctuations are often associated with the pseudogap phase of the copper-oxide superconductors. However, the same fluctuations exist in the overdoped part of the phase diagram where the pseudogap is absent, suggesting that phase fluctuations are independent of the pseudogap In underdoped cuprate superconductors, phase stiffness is low and long-range superconducting order is destroyed readily by thermally generated vortices (and anti-vortices), giving rise to a broad temperature regime above the zero-resistive state in which the superconducting phase is incoherent1,2,3,4. It has often been suggested that these vortex-like excitations are related to the normal-state pseudogap or some interaction between the pseudogap state and the superconducting state5,6,7,8,9,10. However, to elucidate the precise relationship between the pseudogap and superconductivity, it is important to establish whether this broad phase-fluctuation regime vanishes, along with the pseudogap11, in the slightly overdoped region of the phase diagram where the superfluid pair density and correlation energy are both maximal12. Here we show, by tracking the restoration of the normal-state magnetoresistance in overdoped La2−xSrxCuO4, that the phase-fluctuation regime remains broad across the entire superconducting composition range. The universal low phase stiffness is shown to be correlated with a low superfluid density1, a characteristic of both underdoped and overdoped cuprates12,13,14. The formation of the pseudogap, by inference, is therefore both independent of and distinct from superconductivity.

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Nature Physics

Tập 7

455-458

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