Dirac quasiparticle tunneling in a NG/ferromagnetic barrier/SG graphene junction

Effect of Virtual Andreev Reflection on Tunneling in Normal/Superconductor Graphene Junction

“…As we have seen the behavior of the density of state, the junction will be insulating when M < |E FN + E|, saying that current cannot flow in this regime. We also note that the tunneling conductances in the previous studies [9][10][11][12][13][14][15], which were calculated based on the original formulism of Ref. [8], agree with the formalism of G = G i .…”

“…We have modified tunneling conductance formalism by taking into account the current induced by the evanescent type of the Andreev process. This effect has not been considered in the previous studies [8][9][10][11][12][13][14][15]. We have shown that the VAR-processinduced current is found to occur when the excited energy is larger than the energy gap of the superconductor.…”

“…The VAR takes place at the interface in this evanescent mode of HLQ. We note that this process has not been considered in all previous works [8][9][10][11][12][13][14][15]. By matching the boundary condition in (6) and the wave function in (4), the amplitudes of the Andreev reflection "a" and the normal reflection "b" are given by …”

“…This work [8] could be regarded as an original formulism to clarify the Andreev process in graphene-based NG/SG interface. Motivated by this work, the theoretical studies of graphene-based superconducting junction have drawn much attention [9][10][11][12][13][14][15].…”

“…The evanescent type of the Andreev reflection should also occur above the critical angle, similar to that in the F/S conventional junction [17,18] although in graphene the system is not ferromagneticinduced evanescent type of Andreev reflection. However, the previous work [9] has neglected the effect of the Virtual Andreev reflection process above the critical angle, as well as all previous works did [10][11][12][13][14][15].…”