Linear polarization of the photoluminescence of quantum wells subject to in-plane magnetic fields

The degree and orientation of the magnetic-field induced linear polarization of the photoluminescence from a wide range of heterostructures containing (001) (Cd,Mn)Te quantum wells between (Cd,Mn,Mg)Te barriers has been studied as a function of detection photon energy and of the strength and direction of a magnetic field applied in the plane of the quantum well. Three field-induced contributions to the linear polarization of the photoluminescence are observed which differ in their dependence on the angle, phi, between the magnetic field and the [110] direction, being, respectively, independent of phi, varying as cos(2 phi), and as cos(4 phi). A theoretical description of each of these contributions in terms of an in-plane deformation acting on the valence band states is presented and verified by comparison with the experimental data. In our model, we account for the possibility that the in-plane deformations are distributed in both magnitude and direction. We conclude that it is possible to account for the magnetic-field induced linear polarization of the photoluminescence via in-plane deformations and without invoking terms in the valence band spin Hamiltonian which are cubic in J. The models developed in the present paper apply in full measure to nonmagnetic quantum wells as well as ensembles of disklike quantum dots with shape and/or strain anisotropy.