Distribution of Supercurrent Switching in Graphene under the Proximity Effect (original) (raw)
Related papers
Distribution of supercurrent switching in graphene under proximity effect
2011
We study the stochastic nature of switching current in hysteretic current-voltage characteristics of superconductor-graphene-superconductor (SGS) junctions. We find that the dispersion of the switching current distribution scales with temperature as a power law with the power close to 1/3. This observation is in sharp contrast with the known Josephson junction behavior where switching current dispersion is expected to scale with
Josephson super-current in graphene-superconductor junction
Physical review. B, Condensed matter
Within the tunneling Hamiltonian formulation for the eight-component spinors,the Josephson critical super-current has been calculated in a planar superconductor-normal graphene-superconductor junction. Coupling between superconductor regions and graphene is taken into account by a tunneling Hamiltonian which contains two types of tunneling, intra-valley and inter-valley tunneling. Within the present tunneling approach, we find that the contributions of two kinds of tunneling to the critical super-current, are completely separable. Therefore, it is possible to consider the effect of the inter-valley tunnelings in the critical super-current. The incorporation of these type of processes into the tunneling Hamiltonian, exposes a special feature of the graphene Josephson junctions. The effect of inter-valley tunneling appears in the length dependence plot of critical current in the form of oscillations. We also present the results for temperature dependence of critical super-current and ...
Graphene-based Josephson junctions have attracted significant interest as a novel system to study the proximity effect due to graphene's unique electronic spectrum and the possibility to tune junction properties by gate voltage. Here we describe graphene junctions with the mean free path of several micrometers, low contact resistance and large supercurrents. Such devices exhibit pronounced Fabry-Perot oscillations not only in the normal-state resistance but also in the critical current. The proximity effect is mostly suppressed in magnetic fields of <10 mT, showing the conventional Fraunhofer pattern. Unexpectedly, some proximity survives even in fields as high as 1 T. Superconducting states randomly appear and disappear as a function of field and carrier concentration, and each of them exhibits a supercurrent carrying capacity close to the universal limit of eD/h where D is the superconducting gap, e the electron charge and h Planck's constant. We attribute the high-fiel...