Surface Berry plasmons in magnetic semiconductors

The concept of ``surface Berry plasmons" is studied in the concrete instance of a magnetic semiconductor in which the Berry curvature, generated by atomic spin-orbit interaction, has opposite signs for carriers spin parallel or antiparallel to the magnetization. By using collisionless hydrodynamic equations with appropriate boundary conditions, we study both the surface plasmons of a three-dimensional magnetic semiconductor and the edge plasmons of a two-dimensional one. In the 3D case we calculate the dependence of the plasmon frequency on the angle between the direction of propagation and the bulk magnetization. In the 2D case we find that the frequency of the plasmon depends on the direction of propagation along the edge. These Berry curvature effects are compared and contrasted with the anisotropies induced in the plasmon dispersion by an external magnetic field in the absence of Berry curvature. We argue that Berry curvature effects may be used to control the direction of propagation of the surface plasmons, and create a link between plasmonics and spintronics.