Resistive state triggered by vortex entry in YBa2Cu3O7−δ nanostructures

• We have fabricated YBCO nanowires with cross sections down to 50 × 50 nm2.
• We measured the R(T) of these nanowires close to the superconducting transition.
• We analyzed the transition broadening with a thermally activated vortex entry model.
• We extracted reasonable values of λ0 = 270 nm and ξ0 = 2 nm.
• The λ0 value is confirmed by the analyses of IC(B) modulations in Dayem bridge nanoSQUIDs.

We have realized YBa2Cu3O7−δ nanowires and nano Superconducting Quantum Interference Devices (nanoSQUID). The measured temperature dependence of the wire resistances below the superconducting transition temperature has been analyzed using a thermally activated vortex entry model valid for wires wider than the superconducting coherence length. The extracted zero temperature values of the London penetration depth, λ0≃270±15nm, are in good agreement with the value obtained from critical current modulations as a function of an externally applied magnetic field in a nanoSQUID implementing two nanowires.