Probing picosecond depairing currents in type-II superconductors
2 days ago
- Picosecond electrical pulses can drive supercurrents to the intrinsic depairing limit in type-II superconductors by bypassing vortex motion and self-heating.
- Experiments on NbN (s-wave) show a sharp onset of depairing at about 2.2 times the conventional critical current density, consistent with Bardeen–Cooper–Schrieffer (BCS) theory.
- In YBa2Cu3O7 (d-wave), superconductivity is suppressed gradually with increasing current, reflecting the absence of a well-defined depairing threshold due to the nodal d-wave gap.
- The observed effects are attributed to Cooper-pair depairing rather than vortex dynamics, supported by zero-field cooling, picosecond timescales, and the distinct gap-symmetry-dependent responses.
- These results offer a new probe of microscopic superconducting properties and a route to superconducting electronics operating near intrinsic current limits and to ultrashort strong magnetic field pulses.