Microluminescence from a diluted magnetic semiconductor quantum well in a proximity of an iron micromagnet

We describe a method of fabrication and investigation of hybrid quantum structures consisting of a diluted magnetic semiconductor Cd0.96Mn0.04Te quantum well buried immediately beneath the surface on which Fe islands with micrometric lateral dimensions were deposited. The sample was characterized by photoluminescence prior to Fe deposition and, later, by atomic force microscopy. The sample was then placed in a superconducting magnet, magnetized in a field of 5 T perpendicular to the sample plane and examined at T=1.7 K by microluminescence (μ-PL), beginning with the field reduced to zero. An additional peak appeared in the case when the excitation and observation spot was positioned near the Fe island, the additional peak being particularly pronounced when it was excited and observed close to its corner. Magnetic field behavior of this additional peak was studied with the changing field in an increasing and decreasing direction. Its shift in a magnetic field perpendicular to the sample was found to be different from that of the PL peak ascribed to the two-dimensional quantum well excitons. A trace of a hysteresis as well as a degree of σ+ circular polarization of the extra peak are detected. We ascribe the additional peak as due to additional localization of excitons in a potential minimum produced by a fringe magnetic field of a domain formed in the micromagnet.