Confinement of two-dimensional excitons in a nonhomogeneous magnetic field

The effective Hamiltonian describing the motion of an exciton in an externa l nonhomogeneous magnetic field is derived. The magnetic field plays the ro le of an effective potential for the exciton motion, which results in an in crement bf the exciton mass, and modifies the exciton kinetic-energy operat or. In contrast to the homogeneous field case, the exciton in a nonhomogene ous magnetic field can also be trapped in the low-field region and the fiel d gradient increases the exciton confinement. The trapping energy and wave function of the exciton in a GaAs two-dimensional electron gas for specific circular magnetic field configurations are calculated. The results show th at excitons can be trapped by nonhomogeneous magnetic fields, and that the trapping energy is strongly correlated with the shape and strength of the n onhomogeneous magnetic field profile.