Magnetic tailoring of the nature of the fundamental optical transition in a ZnSe/(Zn,Mn)Se heterostructure

We report on optical measurements performed on two 53 and 106 Å wide ZnSe quantum wells separated by a 350-Å-thick ${\mathrm{Zn}}_{0.73}$ ${\mathrm{Mn}}_{0.27}$Se barrier. The measurements were done by means of cw photoluminescence, cw photoluminescence excitation, and time-resolved photoluminescence spectroscopies at low temperature and under a magnetic field up to 5.5 T. They allow us to determine the strain state of the different layers and the valence-band offset between the ternary and binary alloys. Moreover magnetic tailoring of the nature of the fundamental optical transition from a type-I light-hole exciton to a type-II heavy-hole exciton is evidenced. Calculations taking into account the strain, Zeeman, and excitonic effects are presented and support the experimental findings.