Tunneling Conductance of Graphene NIS Junctions

Abstract

We show that, in contrast with conventional normal metal-insulator-superconductor (NIS) junctions, the tunneling conductance of a NIS junction in graphene is an oscillatory function of the effective barrier strength of the insulating region, in the limit of a thin barrier. The amplitude of these oscillations is maximum for aligned Fermi surfaces of the normal and superconducting regions and vanishes for a large Fermi surface mismatch. The zero-bias tunneling conductance, in sharp contrast to its counterpart in conventional NIS junctions, becomes maximum for a finite barrier strength. We also suggest experiments to test these predictions.

Thermal transport properties of graphene-based ferromagnetic/singlet superconductor/ferromagnetic junctions

“…Klein's paradox and from other side its high mobility and controllable Fermi energy in experiment make it very interesting and suitable in laboratory and industry 1,18,19 . From application point of view, it is very important to know the transport properties (charge, spin and thermal transport properties) of the devices including graphene junctions 17,[20][21][22][23][24] .…”

Josephson current in ballistic superconductor-graphene systems

“…17 Subsequently, numerous other theoretical works investigated the Josephson current in SGS structures. 14,[18][19][20][21][22][23] The tunneling effect in SG structures has been studied in several works [24][25][26][27][28] as well. Other works in the field of graphene-superconductor heterostructures include studies on crossed Andreev reflection in a graphene bipolar transistor, 29,30 on s-and d-wave SG junctions 31,32 and on ferromagnetic SG structures.…”

Josephson junction detectors for Majorana modes and Dirac fermions

“…To analyze the property of this circuit, we first consider the Josephson junction. In our proposal, this comprises of two superconductors with order parameters ∆ R (for x > d/2) and ∆ L (for x < −d/2) separated by a barrier region of width d (−d/2 ≤ x ≤ d/2) characterized by a barrier potential V 0 as shown in Fig 1. The superconductors can either be topological superconductors with (effective) p-wave pairing 6,7 or superconductors with Dirac-like quasiparticles which has s-wave pair-potential 16,17,24,25 . In this section, we analyze the former case in details.…”

“…These materials are commonly dubbed as Dirac materials; graphene and topological insulators are common examples of such materials 14,15 . These materials can exhibit superconductivity via proximity effect with Cooper pairing occurring between Dirac electrons with opposite momentum 16,17 ; it is well known that transport properties of such superconductors differ from their conventional counterparts and can serve as experimental signatures of the Dirac nature of their constituent quasiparticles 16,17 .…”