Quantum charge pumping through resonant crossed Andreev reflection in superconducting hybrid junction of Silicene

TL;DR

This paper theoretically demonstrates how adiabatic quantum charge pumping in a silicene-based NISIN junction can achieve perfect crossed Andreev reflection or transmission, with large pumped charge, by tuning external fields and barrier parameters.

Contribution

It introduces a novel silicene NISIN setup that enables control over CAR and transmission resonances for efficient charge pumping, a new approach in superconducting hybrid devices.

Findings

Achieves unity probability of crossed Andreev reflection without transmission or elastic cotunneling.

Large pumped charge (~2e) is possible when the pumping cycle encloses resonance regions.

External electric field and chemical potential tuning enable control over transport processes.

Abstract

We theoretically investigate the phenomena of adiabatic quantum charge pumping through a normal-insulator-superconductor-insulator-normal (NISIN) setup of silicene within the scattering matrix formalism. Assuming thin barrier limit, we consider the strength of the two barriers ($\chi_{1}$ and $\chi_{2}$) as the two pumping parameters in the adiabatic regime. Within this geometry, we obtain crossed Andreev reflection (CAR) with probability unity in the $\chi_{1}$-$\chi_{2}$ plane without concomitant transmission or elastic cotunneling (CT). Tunability of the band gap at the Dirac point by applying an external electric field perpendicular to the silicene sheet and variation of the chemical potential at the normal silicene region, open up the possibility of achieving perfect either CAR or transmission process through our setup. This resonant behavior is periodic with the barrier strengths. We analyze the behavior of the pumped charge through the NISIN structure as a function of the pumping strength and angles of the incident electrons. We show that large ($Q\sim2e$) pumped charge can be obtained through our geometry when the pumping contour encloses either the CAR or transmission resonance in the pumping parameter space. We discuss possible experimental feasibility of our theoretical predictions.