Persistent current distributions along a p-n junction in graphene in a magnetic field

TL;DR

This paper investigates how persistent current distributions along a graphene p-n junction vary with Fermi level changes, highlighting the effects of electron-hole conjugation and the Dirac sea's electromagnetic response, with implications for quantum phenomena exploration.

Contribution

It provides a detailed analysis of persistent currents in graphene p-n junctions, emphasizing the electron-hole symmetry and the Dirac sea's diamagnetic properties, which are novel insights in this context.

Findings

Persistent currents depend on Fermi level variation.

The Dirac sea exhibits intrinsic orbital diamagnetism.

Local currents can be detected with nanoscale magnetometers.

Abstract

A p-n junction, induced in graphene by gating, works to contrast the edge states of electrons and holes on each side of it. In a magnetic field those edge states carry two species of persistent current, which are intimately tied to the edge-mode spectra. We study how those persistent currents change along each side of the junction as the Fermi level is varied, with special emphasis on the electron-hole conjugation property of the Dirac electrons. A close look is made into the electromagnetic response of the valence band filled with negative-energy electrons, or the Dirac sea, which as a whole turns out to be electrically inactive while showing intrinsic orbital diamagnetism. Recently, in experiment, it became possible to observe local currents in planar samples by use of a nanoscale magnetometer. The p-n junctions in graphene and related atomic layers, via detection of associated microscopic currents, will be a useful platform for exploring many-body quantum phenomena.