Accessing phase slip events in Nb meander wires

Abstract

We report transport studies through Nb-based superconducting meander wires fabricated by focused ion beam 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 (T c), 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 (IRSs) during the SC–NM transition. The modulation of the IRSs 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 < 0.5 T c and H ⩽ 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.

Current–voltage characteristics of focused ion beam fabricated superconducting tungsten meanders

“…We attribute the slight disagreement (b < 0.1) of MW2 and MW3 with respect to the WL-TAPS mechanism to the higher width (possess lower disorderness) of meander which is even beyond the Bell's limit [58] for showing signature of TAPS/ QPS. Similarly, for meander samples of Nb [26] and NbN, [34] and Nb 2 PdS 5 wire [35], which have sample dimensions quasi-1D to 3D limitations, the TAPS fitting existence is reported due to their disorder nature. However, the TAPS processes are unexpected for such samples because these are purely 1D superconductor related phenomena.…”

“…The occurrence of PS features [22][23][24][25][26][27][28][29][30] is generally attributed to the fluctuation of condensate wave function due to the spatial and temporal restrictions of the dimensional limitations or phase fluctuations in a superconducting system with reduced dimensions of the order of coherence length (x). Nevertheless, the PS features in the form of TAPS [23,[29][30][31] and QPS [24,25,[31][32][33] have been observed even for systems [18,[26][27][28][34][35][36] with physical dimensions higher than the coherence length. An interested reader may find that there are a number of reports, [18,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] in which the PS signatures in the form of TAPS, QPS in resistance-temperature transition below T C and intermediate resistive steps (IRS) in current-voltage characteristics (IVC) were reported for different nanostructures fabricated by FIB and other techniques.…”

“…Nevertheless, the PS features in the form of TAPS [23,[29][30][31] and QPS [24,25,[31][32][33] have been observed even for systems [18,[26][27][28][34][35][36] with physical dimensions higher than the coherence length. An interested reader may find that there are a number of reports, [18,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] in which the PS signatures in the form of TAPS, QPS in resistance-temperature transition below T C and intermediate resistive steps (IRS) in current-voltage characteristics (IVC) were reported for different nanostructures fabricated by FIB and other techniques. These PS features may evolve with respect to external parameters such as-magnetic field and temperature and can get suppress after a certain limit values.…”

Phase fluctuations in conventional superconductors

“…The phenomenon of thermally activated phase slips have been studied extensively in nanometers wide superconducting wires, grown either through templated growth on nanowires [45] or fabricated through lithographic techniques [46]. We refer the interested reader to an earlier review [22] on this subject by A Bezryadin.…”

Diffusion mediated growth of superconducting Nb-Ti composite films by high temperature annealing

“…Disordered superconductors with high normal state resistance (R N ) are ideal candidates for phase slip (PS) studies where due to continuous phase fluctuations of the superconducting order parameter, resistive tailing is observed in reduced dimension [6][7][8]. A phase slip event driven by the thermal fluctuations near the transition temperature (T C ) is known as thermally activated phase slip and far below the T C , quantum phase slips occur due to quantum tunneling [9].…”