Orbital Diamagnetism of Weak-doped Bilayer Graphene in Magnetic Field

TL;DR

This paper analytically studies the orbital diamagnetism of weakly doped bilayer graphene in varying magnetic fields, revealing complex screening behavior and unique magnetic responses compared to monolayer graphene and 2DEG.

Contribution

It provides the first general analytic expression for the orbital susceptibility of bilayer graphene with finite wave number and Fermi energy at zero temperature.

Findings

Magnetic field screening factor depends on wave number.

Induced magnetization and current differ from monolayer graphene and 2DEG.

Diamagnetic force repels magnetic objects, similar to mirror image effect.

Abstract

We investigate the orbital diamagnetism of a weak-doped bilayer graphene (BLG) in spatially smoothly varying magnetic field and obtain the general analytic expression of the orbital susceptibility of BLG, with finite wave number and Fermi energy, at zero temperature. We find that the magnetic field screening factor of BLG is dependent with the wave number, which results in a more complicated screening behavior compared with that of monolayer graphene (MLG). We also study the induced magnetization, electric current in BLG, under nonuniform magnetic field, and find that they are qualitatively different from that in MLG and two-dimensional electron gas (2DEG). However, similar to the MLG, the magnetic object placed above BLG is repelled by a diamagnetic force from BLG, approximately equivalent to a force produced by its mirror image on the other side of BLG with a reduced amplitude dependent with the typical length of the systems. BLG shows crossover behaviors in the responses to the external magnetic field as the intermediate between MLG and 2DEG.