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One of the few undisputed facts about hole-doped high-Tc cuprates is that their superconducting gap Δ has d-wave symmetry. According to 'dirty' d-wave BCS theory, even structural (non-magnetic) disorder can suppress Δ, the transition temperature Tc and the superfluid density ps. The degree to which the latter is affected by disorder depends on the nature of the scattering. By contrast, Tc is only sensitive to the total elastic scattering rate (as estimated from the residual resistivity p0) and should follow the Abrikosov-Gor'kov pair-breaking formula. Here, we report a remarkable robustness of Tc in a set of Bi2201 single crystals to large variations in p0. We also survey an extended body of data, both recent and historical, on the LSCO family which challenge key predictions from dirty d-wave theory. We discuss the possible causes of these discrepancies, and argue that either we do not understand the nature of disorder in cuprates, or that the dirty d-wave scenario is not an appropriate framework. Finally, we present an alternative (non-BCS) scenario that may account for the fact that the superconducting dome in Tl2201 extends beyond that seen in Bi2201 and LSCO and suggest ways to test the validity of such a scenario. [ABSTRACT FROM AUTHOR]

AbstractPhysical measurements of the normal state of an unconventional or high-temperature superconductor in the zero-temperature limit can provide vital information on the nature of the electronic ground state from which the superconductivity emerges. Viable routes to fully suppress the superconductivity include the application of magnetic fields stronger than the upper critical field Hc2 or current densities larger than the critical current density Jc. In high-Tc superconductors, Hc2 is typically higher than the available field strengths, while high currents can often create large heating effects that cause irreparable damage to the sample. Here, we present a technique that combines intense current pulses with high magnetic fields to fully suppress the superconductivity of a candidate high-Tc superconductor while keeping both J and μ0H below their critical values. Two adaptable circuit designs are presented with negligible stray field or self-heating effects (below a critical current value). As a proof of principle, we apply the technique to a high-Tc cuprate with nominal μ0Hc2 ∼ 36 T and demonstrate the suppression of superconductivity down to T/Tc ≤ 0.1 in a field strength of just 24 T. Further applications of this dual technique are also discussed. [ABSTRACT FROM AUTHOR]