Chemical and magnetic profile of magnetic semiconductors as probed by polarized neutron reflectivity

We investigate the depth dependence of magnetic species in co-doped dilute magnetic semiconductor (DMS) specimens. We also compare the reliability of the nuclear and magnetization depth profile of these specimens on different polarized neutron reflectivity instruments. These reflectometers were not only angle dispersive instruments but also wavelength dispersive instruments. Measurements indicate a segregation of DMS species onto the top into the cap layer for lower Fe doping. However, for higher Fe doping, as we alter the doping concentrations of magnetic species, no segregation and lower clustering tendencies are indicated. Thus sensitive depth profiling, for specimens with such low magnetic-ion concentrations, may not be a challenge for brighter sources and careful measurements. Our results show that homogeneity can be achieved with Fe co-doping within a Ge matrix which can make it a potential candidate for spintronic applications.