Spontaneous symmetry breaking of magnetic polarons in low-dimensional semimagnetic structures

We have shown that magnetic polarons in symmetric low-dimensional structures with magnetic barriers undergo a bifurcation from a symmetric state to an asymmetric one at increasing magnetic coupling constant. We present a criterion for the occurence of bifurcation for the quasi-one-dimensional (1D) and quasi-2D cases. This criterion has been derived by analysis of symmetric state stability with respect to a virtual displacement of the polaron wave function. The complete numerical solution of the corresponding nonlinear Schrodinger equation has been obtained below and above the bifurcation in the quasi-1D case. The critical exponents for free energy, energy, and wave-function center of gravity are discussed. Extension to the interface magnetic polaron is presented. The binding of a 3D free magnetic polaron to a 2D quantum well is treated perturbatively. Extension to the exciton case is outlined. The possible observation of the aforementioned experimental effects is discussed.