Effects of interface imperfections on the Zeeman splitting of excitons in diluted magnetic semiconductor quantum wells

Theoretical estimates are given of the influence that imperfect interfaces have on the Zeeman splittings of excitons in diluted magnetic semiconductor quantum well structures in which one or both of the barriers are magnetic. A first-principles theoretical treatment of the microscopic magnetic response of the interfaces has been utilized in the calculations. The results show how sensitive these splittings can be to even the smallest degree of imperfection at the interface region provided that both barriers are magnetic and the initial potential profile is symmetric with respect to the centre of the well. A comparison with experimental data on the CdTe/Cd₁-_xMn_xTe system shows that all such symmetric quantum well structures reported to date have imperfections at the interface region extending over at least one or two monolayers. The calculations also show that asymmetric quantum well structures, in which one of the barriers is non-magnetic, can be a far less sensitive probe of interface imperfections.