Geometry-related magnetic interference patterns in longSNSJosephson junctions

Abstract

We have measured the critical current dependence on the magnetic flux of two long SNS junctions differing by the normal wire geometry. The samples are made by a Au wire connected to W contacts, via focused ion beam assisted deposition. We could tune the magnetic pattern from the monotonic Gaussian-like decay of a quasi-one-dimensional (1D) normal wire to the Fraunhofer-like pattern of a square normal wire. We explain the monotonic limit with a semiclassical 1D model, and we fit both field dependencies with numerical simulations of the two-dimensional Usadel equations. Furthermore, we observe both integer and fractional Shapiro steps. The magnetic flux dependence of the integer steps reproduces as expected that of the critical current I c , while fractional steps decay slower with the flux than I c .

Crossed Andreev reflection in InSb flake Josephson junctions

“…The measured SQI pattern at V BG = −0.3 V is well reproduced by the theoritical curves for a (quasi) 1D JJ [ Fig. 3(c)], as described [27,36] and observed before [36,37]. Entering the 1D regime is in line with having a single edge with (110) facet and enhanced edge conduction in JJ2 [ Fig.…”

Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

“…The vortices could be detected directly by a scanning tunneling probe [31][32][33], or indirectly through the fluxdependent Fraunhofer oscillations [34,35]-we have found that the transition from a 1D to a 2D arrangement of vortices is accompanied by a slow-down of the decay of the oscillation amplitude from 1/ to 1/ √ . A particularly intriguing feature of the current vortex lattice is the reconstruction at the edge, resulting in an edge channel of width l m parametrically larger than the lattice constant.…”

Orbital Josephson interference in a nanowire proximity-effect junction

“…For junction widths comparable to the S-section coherence length, i.e. the narrow junction limit, this becomes a quasi-Gaussian, monotonic decay of the critical current 7,10,11 . Recently, attention has been given to nanoscale, quasi one-dimensional (1D) SN S junctions, such as those readily engineered by contacting semiconductor nanowires with superconducting leads [12][13][14][15][16] .…”

“…Planar SN S junctions of width large compared to the S-section superconducting coherence length have been studied in great detail 6 (width refers to the dimension perpendicular to the current). These have revealed, for example, Fraunhofer oscillations of the critical current I c with respect to an externally applied out-of-plane magnetic field [7][8][9] . For junction widths comparable to the S-section coherence length, i.e.…”