Thickness dependent interlayer transport in vertical MoS2 Josephson   junctions
  We report on observations of thickness dependent Josephson coupling and multiple Andreev reflections (MAR) in vertically stacked molybdenum disulfide (MoS2) - molybdenum rhenium (MoRe) Josephson junctions. MoRe, a chemically inert superconductor, allows for oxide free fabrication of high transparency vertical MoS2 devices. Single and bilayer MoS2 junctions display relatively large critical currents (up to 2.5 uA) and the appearance of sub-gap structure given by MAR. In three and four layer thick devices we observe orders of magnitude lower critical currents (sub-nA) and reduced quasiparticle gaps due to proximitized MoS2 layers in contact with MoRe. We anticipate that this device architecture could be easily extended to other 2D materials. 
Joshua O. Island, Gary A. Steele, Herre S.J. van der Zant, Andres   Castellanos-Gomez
cond-mat.mes-hall cond-mat.supr-con