부산대학교 도서관

The interplay between charge transfer and electronic disorder in transition-metal dichalcogenide multilayers gives rise to superconductive coupling driven by proximity enhancement, tunneling and superconducting fluctuations, of a yet unwieldy variety. Artificial spacer layers introduced with atomic precision change the density of states by charge transfer. Here, we tune the superconductive coupling between NbSe$_2$ monolayers from proximity-enhanced to tunneling-dominated. We correlate normal and superconducting properties in [(SnSe)$_{1+{\delta}}$]$_m$[NbSe$_2$]$_1$ tailored multilayers with varying SnSe layer thickness. From high-field magnetotransport the critical fields yield Ginzburg-Landau coherence lengths with an increase of 140 % cross-plane , trending towards two-dimensional superconductivity for m > 9. We show cross-over between three regimes: metallic with proximity-enhanced coupling, disordered-metallic with intermediate coupling and insulating with Josephson tunneling. Our results demonstrate that stacking metal mono- and dichalcogenides allows to convert a metal/superconductor into an insulator/superconductor system, prospecting the control of two-dimensional superconductivity in embedded layers.
Comment: Revised version submitted to Journal of Physics: Condensed Matter