Magnetic depth profiling of Fe3O4/SrTiO3 heterostructures to reveal dynamics of interfacial switching

Controlling the oxide interfaces is the key towards controlling the switching phenomenon and thus realizing functional devices. We found that oxide substrates can take an active part in the redox process at the interface and may be even used to tune properties. Hence, our next goal is to real-time monitor the redox reactions at the interface when the properties or "iron oxide phases" of the interfaces and the films are tuned.
We have characterized our samples using different lab techniques, e.g. XRR, XRD, SQUID and GISAXS, or using large scale X-ray facilities, e.g. HAXPES and XMCD. Using SQUID, we observe the disappearance of Verwey transition, the characteristic temperature for Fe3O4, when applying a positive voltage. This indicates a perturbation of oxygen content in the Fe3O4 phase and possible switching to the insulator gamma-Fe2O3 phase at the interface. Thus, our next step is to monitor in-situ the magnetic depth profiling when applied electric field using polarized neutron reflectivity in order to real-time monitor the thickness and the composition of the intralayer.