Accessing Phase Slip Events in Nb Meander Wires

TL;DR

This study investigates phase slip events in Nb superconducting meander wires fabricated by FIB, revealing how meandering affects quantum transport, phase slip mechanisms, and their modulation by temperature and magnetic field.

Contribution

It provides experimental evidence of phase slip phenomena in Nb meander wires and analyzes their behavior under varying conditions, advancing understanding of quantum transport in superconducting nanostructures.

Findings

Meandering broadens the normal-superconductor transition.

Resistive tailing explained by thermally activated phase slips.

Magnetic fields facilitate phase slip events up to 250 mT.

Abstract

We report transport studies through Nb-based superconducting meander wires fabricated by focused ion beam (FIB) milling technique. The effect of meandering on quantum transport has been probed experimentally by a direct comparison with the pristine thin-film device before meandering. The normal metal (NM) to superconductor (SC) phase transition becomes a wide and multi-step transition by meandering. Below the transition temperature (Tc), the resistance-versus-temperature measurements reveal resistive tailing which is explained by the thermally activated phase slip (TAPS) mechanism. The TAPS fit indicates a selective region of the meander to be responsible for the resistive tailing. Besides, the phase slip (PS) mechanism in the meander is evident in its current-voltage characteristics that feature the stair-case type intermediate resistive steps during the SC-NM transition. The modulation of the intermediate resistive steps is investigated with respect to temperature and external magnetic field. It is observed that the PS events are facilitated by magnetic fields up to about 250 mT. Further, the critical current varies strongly on the temperature and magnetic field for T less than 0.5Tc and H less tahn 100 mT where it fluctuates in an oscillatory manner. Finally, Nb based meander structures can be promising candidates for future PS based studies and applications.