Inhomogeneous magnetic fields are used to exert a magnetic force on two-dim
ensional excitons. The large field gradients are produced by positioning a
thin magnetized stripe of dysprosium on top of a semi-magnetic CdMnTe/CdMgT
e quantum well. By measuring the photoluminescence energy and intensity, sp
atially resolved with mu m resolution, the actual value of the local magnet
ic force, which can be as high as 0.4 meV/mu m, and its effect on the excit
on motion are determined.