Quantum transport of pseudospin-polarized Dirac fermions in gapped graphene nanostructures

TL;DR

This paper explores quantum transport phenomena in gapped graphene with pseudospin polarization, proposing a pseudospin valve effect and analyzing Andreev reflection, revealing behaviors akin to ferromagnetic graphene.

Contribution

It introduces a pseudospin valve effect in gapped graphene and studies pseudospin-related phenomena in hybrid structures, highlighting the pseudospin's role similar to spin in ferromagnetic materials.

Findings

Pseudospin valve effect enables pseudospintronics in graphene.

Unique Andreev reflection linked to pseudospin inversion.

Gapped graphene exhibits ferromagnetic-like pseudospin behavior.

Abstract

We investigate the unusual features of the quantum transport in gapped monolayer graphene, which is in a pseudospin symmetry-broken state with a net perpendicular pseudomagnetization. Using these pseudoferromagnets (PFs), we propose a perfect pseudospin valve effect that can be used for realizing pseudospintronics in monolayer graphene. The peculiarity of the associated effects of pseudo spin injection and pseudo spin accumulation are also studied. We further demonstrate the determining effect of the sublattice pseudospin degree of freedom on Andreev reflection and the associated proximity effect in hybrid structures of PFs and a superconductor in S/PF and PF/S/PF geometries. In particular, we find a peculiar Andreev reflection that is associated with an inversion of the z component of the carriers pseudospin vector. Our results show that the gapped normal graphene behaves like a ferromagnetic graphene and the effect of the pseudospin degree of freedom in gapped graphene is as important as the spin in a ferromagnetic graphene.