We present a low-energy effective-mass theory to describe a chiral orbital current and an anomalous magnetic moment in graphenes with a band gap and related materials. We explicitly derive a quantum-mechanical current distribution in general Bloch electron systems, which describes a chiral current circulation supporting the magnetic moment. We apply the formulation to gapped graphene monolayer, bilayer, and ABC-stacked multilayers to show that the chiral current is opposite between different valleys, and the corresponding magnetic moment accounts for valley splitting of Landau levels. In a gapped bilayer and ABC multilayer graphenes, in particular, the valley-dependent magnetic moment is responsible for huge paramagnetic susceptibility at low energy, which enables a full valley polarization up to relatively high electron densities. The formulation also applies to the gapped surface states of a three-dimensional topological insulator, where the anomalous current is related to the magnetoelectric response in a spatially modulated potential.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Sep 12|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics