YBa2Cu3O7−δ nanorings to probe fluxoid quantization in High Critical Temperature Superconductors

• We fabricated YBCO nanorings, whose arms have cross sections down to 50 × 30 nm2.
• We measured the magnetoresistance R(B)R(B) close to the superconducting transition.
• Large R(B)R(B) oscillations have been interpreted in terms of vortex dynamics.
• The FFT peak of the R(B)R(B) oscillations can be associated to a h/2eh/2e periodicity.
• The homogeneity in the rings favors a uniform vorticity of the order parameter.

We have realized YBa2Cu3O7−δ (YBCO) nanorings and measured the magnetoresistance R(B)R(B) close to the superconducting transition. The large oscillations that we have measured can be interpreted in terms of vortex dynamics triggering the nanowires to the resistive state. The Fast Fourier Transform spectrum of the magnetoresistance oscillations shows a single sharp peak for nanorings with narrower loop arm width: this peak can be univocally associated to a h/2eh/2e periodicity as predicted for optimally doped YBCO. Moreover it is a clear evidence of a uniform vorticity of the order parameter inside the rings, confirming a high degree of homogeneity of our nanostructures. This result gives a boost to further investigations of YBCO nanorings at different dopings within the superconducting dome, where in the underdoped regime a R(B)R(B) periodicity different from the conventional h/2eh/2e has been predicted.