High field vortex matching effects in superconducting Nb thin films with a nanometer-sized square array of antidots

Abstract

Articles you may be interested inPerpendicular applied magnetic field dependence of Josephson current and measurement of trapped magnetic flux in Nb superconducting thin film by vibrating sample magnetometer Nb thin films containing a regular square array of antidots with 17 nm diameter and 50 nm spacing have been fabricated using a relatively simple lithographic process. The critical current density j c ͑H͒ curves, obtained here by electric transport measurements, exhibit commensurability effects with pronounced maxima just above the expected 0 H 1 = 0.830 T and 0 H 1/2 = 0.415 T matching fields, down to temperatures as low as 2.3 K. The behavior of j c ͑H͒ as well as the position of the maxima are consistent with the ones calculated in the framework of the time dependent Ginzburg-Landau model.

Nonlinear current-voltage characteristics due to quantum tunneling of phase slips in superconducting Nb nanowire networks

“…[19] As a consequence, also the zero temperature depairing current density [26] of the single wire j dp (0) = j dp (t)(1 − t) −1.5 ∼ [i dp (t)(1 − t) −1.5 ]/σ 2 ≃ 1.9 × 10 10 A/m 2 is comparable to the one reported in the case of the network with N = 250 and in the case of perforated Nb films. [19,27] This result indicates that the further reduction of N does not significantly depress the superconducting properties of the single wire and confirms, again, the good quality of the sample ruling out the presence of tunneling barriers at the grain boundaries. [16] In Fig.…”

Phase slippage driven dissipation and high-field Little-Parks effect in superconducting MoGe nanowire networks formed on nanoporous substrates

“…anodic aluminum oxide (AAO) have been pursued as substrates for introducing vortex pinning centers of high density into superconducting films. [45][46][47][48] Commensurate vortex pinning, i.e. when an integer number of flux quantum, is commensurate with the unit-cell of the hole-array superconductor, can also induce similar anomalies in the magnetoresistance as those expected from the Little-Parks effect.…”

“…The pores with diameter of ~20 nm in the substrate also enable us to conveniently fabricate multiply connected 1D superconductor with hole-diameter comparable to its zerotemperature coherence length, divulging the behavior of such extreme systems. Furthermore, our results also set limitations on efforts to pursue high commensurate vortex pinning fields by increasing the density of holes in a perforated film: [45][46][47][48] a reduction in the width of superconducting section between neighboring holes will increase the temperature range in which the perforated film 15 behaves as a network of 1D nanowires which dissipate energy when conducting electricity due to thermal and possibly also quantum phase slippages, eliminating the desired pinning effect of the introduced holes. Sample D are given in the inset of (a).…”

Effect of hexagonal patterned arrays and defect geometry on the critical current of superconducting films

“…[1][2][3] Experimentally, defects can be introduced into superconducting films in a controllable fashion using advanced nanofabrication techniques such as focus ion beam (FIB) milling, 4 electron beam lithography (EBL), 5 EBL combined with reactive ion etching, 6,7 or ion irradiation. 8 Many artificial pinning array structures (pinscapes) have been studied experimentally as well as numerically, for example, square arrays of antidots, 7,[9][10][11][12][13][14][15][16][17] hexagonal (or triangular) pinning lattices, 18,19 honeycomb arrays, [20][21][22][23] Penrose lattice arrays, 19,[24][25][26][27][28][29] blind hole arrays, [30][31][32] diluted periodic arrays, 18,33 composite lattices, 34 pinscapes with density gradients, 6,7,29,33,[35][36][37][38] and pinscapes with geometrically frustrated energy landscape. 4,…”