Flux Periodicities in Loops of Nodal Superconductors

Abstract

Supercurrents in superconducting flux threaded loops are expected to oscillate with the magnetic flux with a period of hc/2e. This is indeed true for s-wave superconductors larger than the coherence length xi_0. Here we show that for superconductors with gap nodes, there is no such strict condition for the supercurrent to be hc/2e rather than hc/e periodic. For nodal superconductors, the flux induced Doppler shift of the near nodal states leads to a flux dependent occupation probability of quasi-particles circulating clockwise and counter clockwise around the loop, which leads to an hc/e periodic component of the supercurrent, even at zero temperature. We analyze this phenomenon on a cylinder in an approximative analytic approach and also numerically within the framework of the BCS theory. Specifically for d-wave pairing, we show that the hc/e periodic current component decreases with the inverse radius of the loop and investigate its temperature dependence.

References in corpus (9)

• Scanning tunneling spectroscopy of high-temperature superconductors
• h/e-Periodicity in Superconducting Loops
• Restoration of the magnetic hc/e-periodicity in unconventional superconductors
• Emergence of $h/e$-period oscillations in the critical temperature of small superconducting rings threaded by magnetic flux
• Low-energy subgap states and the magnetic flux periodicity in d-wave superconducting rings
• Crossover from hc/e to hc/2e current oscillations in rings of s-wave superconductors
• Supercurrent in Nodal Superconductors
• Imperfect nanorings with superconducting correlations
• Persistent currents in one dimension: the other side of Leggett's theorem