Crossed Andreev reflection versus electron transfer in graphene nanoribbons

TL;DR

This paper analyzes transport phenomena in three-terminal graphene nanoribbon devices, revealing how device symmetry influences the dominance of electron transfer or crossed Andreev reflection, with implications for quantum transport control.

Contribution

It provides analytical and numerical insights into ET and CAR in symmetric and asymmetric graphene nanoribbon devices, highlighting the role of zero-energy modes.

Findings

ET dominates in symmetric devices

CAR can dominate in asymmetric devices

Zero-energy modes are crucial for transport behavior

Abstract

We investigate the transport properties of three-terminal graphene devices, where one terminal is superconducting and two are normal metals. The terminals are connected by nanoribbons. Electron transfer (ET) and crossed Andreev reflection (CAR) are identified via the non-local signal between the two normal terminals. Analytical expressions for ET and CAR in symmetric devices are found. We compute ET and CAR numerically for asymmetric devices. ET dominates CAR in symmetric devices, but CAR can dominate ET in asymmetric devices, where only the zero-energy modes of the zigzag nanoribbons contribute to the transport.