Superconductive coupling in tailored [(SnSe)(1+delta)](m)(NbSe2)(1) multilayers

摘要

Ferecrystals are a new artificially layered material system, in which the individual layers are stacked with monolayer precision and are turbostratically disordered. Here, the superconducting coupling of the NbSe2 layers in [(SnSe)(1+delta)]m[NbSe2](1) ferecrystals with m between 1 and 6 are investigated. The variation of m effectively increases the distance between the superconducting NbSe2 monolayers. We find a systematic decrease of the transition temperature with an increasing number of SnSe layers per repeat unit. For m = 9 a superconducting transition can no longer be observed at temperatures above 250 mK. In order to investigate the superconducting coupling between individual NbSe2 layers, the cross-plane Ginzburg-Landau coherence lengths were determined. Electric transport measurements of the superconducting transition were performed in the presence of a magnetic field, oriented parallel and perpendicular to the layers, at temperatures closely below the transition temperature. A decoupling with increasing distance of the NbSe2 layers is observed. However, ferecrystals with NbSe2 layers separated by up to six layers of SnSe are still considered as three-dimensional superconductors.