Study of differential shot noise in ferromagnet-insulator-superconductor graphene junction with TRSB

Abstract

In this paper, we study differential shot noise in ferromagnet-insulator- superconductor graphene junction with time-reversal symmetry broken (TRSB) where we consider two different Cooper pairing states: one unconventional TRSB D ​+ ​iS-wave and an unconventional TRSB D ​+ ​iDxy-wave. We consider two regimes: the first one is the equal Fermi energies on both sides of the junction and the second regime is the Fermi energies that are far from each other. In the first regime, for D ​+ ​iS when the main part i. e. D-wave is dominant, we have obtained the shot noise peaks at the edge of the superconducting gap. The height of peaks reduces with the increase of the ferromagnetic exchange field. For D ​+ ​iS, when the s-wave part plays the main role, the peaks split in high exchange fields. For D ​+ ​iDxy-wave, the peaks split as well, but the distance between the peaks for D ​+ ​iDxy is smaller than D ​+ ​iS. Also, differential shot noise at zero-bias shows an oscillating behavior with respect to the barrier potential of the insulator such that its absolute value decreases when the exchange field enhances.In the second regime (Fermi energies are selected far from each other in the both sides of the junction), zero-bias peaks are formed when the main part i. e. D-wave is dominant while the peaks are shifted to non-zero voltages when the sub-dominant s-wave part is significant compared with the main part. Also, differential shot noise at zero-bias does not show any oscillating behavior versus the strength of barrier potential while its absolute value enhances with the increase of the exchange fields.Therefore, differential shot noise may serve as a valuable tool to understand more about various candidates of pair symmetries including TRSB states.