Proximity-induced superconductivity in crystalline Cu and Co nanowires and nanogranular Co structures

Abstract

We report an experimental study of proximity effect-induced superconductivity in crystalline Cu and Co nanowires and a nanogranular Co nanowire structure in contact with a superconducting W-based floating electrode (inducer). For electrical resistance measurements up to three pairs of Pt-based voltage leads were attached at different distances beside the inner inducer electrode, thus allowing us to probe the proximity effect over a length of 2–12 μm. Up to 30% resistance drops with respect to the normal-state value have been observed for the crystalline Co and Cu nanowires when sweeping the temperature below Tc of the inducer (5.2 K). By contrast, relative R(T) drops were found to be an order of magnitude smaller for the nanogranular Co nanowire structure. Our analysis of the resistance data shows that the superconducting proximity length in crystalline Cu and Co is about 1 μm at 2.4 K, attesting to a long-range proximity effect in the Co nanowire. Moreover, this long-range proximity effect is insusceptible to magnetic fields up to 11 T, which is indicative of spin-triplet pairing. At the same time, proximity-induced superconductivity in the nanogranular Co nanowire is strongly suppressed due to the dominating Cooper pair scattering caused by its intrinsic microstructure.

Anomalous magneto-resistance of Ni-nanowire/Nb hybrid system

“…Recently a qualitatively new type of circuit has emerged, in which F-NWs are bonded to superconducting (S) electrodes 18,20 . In ref.…”

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

“…In particular, the ability to tune the magnetization is the basic property needed for the realization of stacked nanomagnets [7], pinning of magnetic domain walls [8] and Abrikosov vortices [9–11], magnetic sensing [5,12] and storage [3–4], and spin-triplet proximity-induced superconductivity [13–17]. This magnetization tuning has been accomplished to a very high degree by means of layered heterostructures in the vertical dimension, which can be prepared by thin film techniques or by an alternative approach, as used by us, namely the direct writing of metal-based layers by focused electron beam induced deposition (FEBID) [18–19].…”

“…Controlling magneto-transport properties on the nanometer-scale is essential for basic research in micro-magnetism [ 1 ] and spin-dependent transport [ 2 ] as well as for various applications, such as magnetic domain-wall logic [ 3 ] and memory [ 4 ], fabrication of Hall sensors [ 5 ] and cantilever tips [ 6 ] for magnetic force microscopy (MFM). In particular, the ability to tune the magnetization is the basic property needed for the realization of stacked nanomagnets [ 7 ], pinning of magnetic domain walls [ 8 ] and Abrikosov vortices [ 9 – 11 ], magnetic sensing [ 5 , 12 ] and storage [ 3 – 4 ], and spin-triplet proximity-induced superconductivity [ 13 – 17 ]. This magnetization tuning has been accomplished to a very high degree by means of layered heterostructures in the vertical dimension, which can be prepared by thin film techniques or by an alternative approach, as used by us, namely the direct writing of metal-based layers by focused electron beam induced deposition (FEBID) [ 18 – 19 ].…”

Superconductivity in the system MoxCyGazOδ prepared by focused ion beam induced deposition

“…Here we specifically mention the fabrication of structures for tunneling spectroscopy 1 or for point contacts in Andreev junctions, e.g., with ferromagnetic counter electrodes 2 and the use of submicron sized superconducting electrodes that induce exotic spin-triplet pairing in ferromagnetic nano wires 3,4 . So far the amorphous superconductor W x C y Ga z O δ prepared by focused ion beam induced deposition with a Ga source (Ga-FIBID) using the precursor W(CO) 6 has been the only example in this regard 5 .…”