Decrease of upper critical field with underdoping in cuprate superconductors

Abstract

The transition temperature Tc of cuprate superconductors falls when the doping p is reduced below a certain optimal value. It is unclear whether this fall is due to strong phase fluctuations or to a decrease in the pairing gap. Different interpretations of photoemission data disagree on the evolution of the pairing gap and different estimates of the upper critical field Hc2 are in sharp contradiction. Here we resolve this contradiction by showing that superconducting fluctuations in the underdoped cuprate Eu-LSCO, measured via the Nernst effect, have a characteristic field scale that falls with underdoping. The critical field Hc2 dips at p = 0.11, showing that superconductivity is weak where stripe order is strong. In the archetypal cuprate superconductor YBCO, Hc2 extracted from other measurements has the same doping dependence, also with a minimum at p = 0.11, again where stripe order is present. We conclude that competing states such as stripe order weaken superconductivity and this, rather than phase fluctuations, causes Tc to fall as cuprates become underdoped.

Supplementary Information file available upon request; Nature Physics (2012)

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Cited by in corpus (5)

• Vortex Lattice Melting and Hc2 in underdoped YBa2Cu3Oy
• Evolution of superconducting correlations within magnetic-field-decoupled CuO(2) layers of La(1.905)Ba(0.095)CuO(4)
• Disparity of superconducting and pseudogap scales in low-Tc Bi-2201 cuprates
• Measurements of the fluctuation-induced in-plane magnetoconductivity at high reduced temperatures and magnetic fields in the iron arsenide BaFe(2-x)NixAs2
• Precursor superconducting diamagnetism in YBa2Cu3O7-d with in-plane or intercalated magnetic impurities