Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene

TL;DR

This paper proposes a hybrid graphene device with a modulated magnetic field to reduce screening effects, enabling electron-hole superfluidity at measurable temperatures, overcoming previous limitations.

Contribution

It introduces a novel magnetic field modulation technique to weaken screening in monolayer graphene, facilitating superfluidity at finite temperatures.

Findings

Magnetic modulation reduces Fermi velocity in graphene.

Weakened screening allows superfluidity at accessible temperatures.

Current experimental setups can implement the proposed device.

Abstract

Experiments have confirmed that double monolayer graphene cannot generate finite temperature electron-hole superfluidity. This has been shown to be due to very strong screening of the electron-hole pairing attraction. The linear dispersing energy bands in monolayer graphene prevent attempts to reduce the strength of the screening. We propose a new hybrid device in which the two sheets of monolayer graphene are placed in a modulated periodic perpendicular magnetic field. Such a magnetic field preserves the isotropic Dirac cones of the original monolayers but it reduces the slope of the cones so that the monolayer Fermi velocity $v_F$ is smaller. We show that with current experimental techniques, this reduction in $v_F$ can sufficiently weaken the screening to permit electron-hole superfluidity at measurable temperatures.