Anomalous equilibrium currents for massive Dirac electrons

Abstract

Existing investigations of the anomalous Hall effect i.e. a current flowing transverse to the electric field in the absence of an external magnetic field) are concerned with the transport current. However, for many applications one needs to know the total current, including its pure magnetization part. In this paper, we employ the two-dimensional massive Dirac equation to find the exact universal total current flowing along a potential step of arbitrary shape. For a spatially slowly varying potential we find the current density $\mathbf{j}(\vec r)$ and the energy distribution of the current density $\mathbf{j}^\varepsilon(\vec r)$. The latter turns out to be unexpectedly nonuniform, behaving like a $\delta$-function at the border of the classically accessible area at energy~$\varepsilon$. To demonstrate explicitly the difference between the magnetization and transport currents we consider the transverse shift of an electron ray in an electric field.