Magnetic trap for excitons

High in-plane magnetic field gradients are used to control the lateral motion of excitons in an InGaAs quantum well. The gradients, as large as 6.10(4) T/m, are produced by positioning a thin magnetized stripe of dysprosium on top of the quantum well. By measuring the exciton photoluminescence energy and intensity, spatially resolved with um resolution, it is shown that the diamagnetic excitons are forced to regions of low magnetic field, because of the interaction of their magnetic moment with the inhomogeneous field. These results show the possibility to magnetically confine excitons to a limited region of space, which opens the way for the realization of the first magnetic trap in solids. (C) 1998 Elsevier Science B.V. All rights reserved.