Pseudospin Electronics in Phosphorene Nanoribbons

TL;DR

This paper introduces pseudospin as a tunable degree of freedom in phosphorene nanoribbons, demonstrating pseudospin-based transistors and valves with high efficiency and robustness, paving the way for novel pseudospin electronic devices.

Contribution

It proposes and characterizes pseudospin field-effect transistors and valves in phosphorene nanoribbons, a novel concept in pseudospin electronics.

Findings

Edge and layer pseudospin can be electrically controlled.

Pseudospin valves exhibit high pseudomagnetoresistance ratios.

Edge-pseudospin valve is highly robust against disorder.

Abstract

Zigzag phosphorene nanoribbons are metallic owing to the edge states, whose energies are inside the gap and far from the bulk bands. We show that -- through electrical manipulation of edge states -- electron propagation can be restricted to one of the ribbon edges or, in case of bilayer phosphorene nanoribbons, to one of the layers. This finding implies that edge and layer can be regarded as tunable equivalents of the spin-one-half degree of freedom, i.e., the pseudospin. In both layer- and edge-pseudospin schemes, we propose and characterize a pseudospin field-effect transistor, which can generate pseudospin-polarized current. Also, we propose edge- and layer-pseudospin valves that operate analogously to conventional spin valves. The performance of valves in each pseudospin scheme is benchmarked by the pseudomagnetoresistance (PMR) ratio. The edge-pseudospin valve shows a nearly perfect PMR, with remarkable robustness against device parameters and disorder. These results may initiate new developments in pseudospin electronics.