Proximity effects in the superconductor/heavy-fermion bilayer system Nb/CeCu ₆

Abstract

Abstract. -We have investigated the proximity effect between a superconductor (Nb) and a 'Heavy Fermion' system (CeCu6) by measuring critical temperatures Tc and parallel critical fields H c2 (T) of Nb films with varying thickness deposited on 75 nm thick films of CeCu6, and comparing the results with the behavior of similar films deposited on the normal metal Cu. For Nb on CeCu6 we find a strong decrease of Tc with decreasing Nb thickness and a finite critical thickness of the order of 10 nm. Also, dimensional crossovers in H c2 (T) are completely absent, in strong contrast with Nb/Cu. Analysis of the data by a proximity effect model based on the Takahashi-Tachiki theory shows that the data can be explained by taking into account both the high effective mass (or low electronic diffusion constant), and the large density of states at the Fermi energy which characterize the Heavy Fermion metal.

Long-range proximity effect in Nb-based heterostructures induced by a magnetically inhomogeneous permalloy layer

“…The DCO in this case seems to be the result of the extended effective S-thickness, with only the proximity of the top S/F interface contributing. A similar DCO, indeed, was observed for a simple Nb/Cu bilayer [34]. Whether the estimated short penetration length, due to ℓ sf , is enough to explain a transition from a 2D to a 3D regime, is unclear.…”

A Review of Electronic Transport in Superconducting Sr2RuO4 Junctions

“…Since these are Uranium compounds, it is restricted to utilising such materials independently to develop the junctions. Still, few groups utilised UPt 3 to study the proximity effect of a heavy fermion superconductor that indicates very low interface transparencies due to fermi surface mismatch at the interface [87].…”

“…In addition to the single crystals, thin films of heavy fermion superconductors can be grown using molecular beam epitaxy (MBE) or sputtering as well [91][92][93], which can be utilised to develop spin-triplet junctions to investigate the superconducting properties and superconducting spin transport. However, the higher effective mass of heavy fermions suppresses the interface transparency and makes it painstaking to develop sufficiently good quality junctions for fundamental and applied research work [87].…”

Andreev reflection and order parameter symmetry in heavy-fermion superconductors: the case of CeCoIn$_5$

“…Further measurements on such junctions but without oxide interface layers will provide important clues to many issues on AR in heavy fermions. A related experiment will be exploring whether proximity effect exists in such junctions [138,139]. The fact that AR is frequently observed in heavy fermions implies that proximity effect should exist because it is well known that AR is at the heart of this phenomenon [140].…”