Thermodynamic stability and control of oxygen reactivity at functional oxide interfaces: EuO on ITO

As a prototypical all-oxide heterostructure, the ferromagnetic insulator europium monoxide (EuO) issynthesized on transparent and conductive indium tin oxide (ITO) virtual substrates. Non-destructivehard X-ray photoelectron spectroscopy is employed to depth profile the chemical composition of themagnetic layer and the buried oxide–oxide interface. We find that thermally activated oxygen diffusionfrom ITO affects the EuO growth process. We present how to control the oxygen reactivity at the interfaceand discuss its origin in a thermodynamic analysis. Our complementary methodical strategy allowsfor a significant improvement of the EuO chemical quality with sizeable magnetic properties. Generally,our approach derives guidelines for the proper choice of oxide substrates and buffer layer materials forfunctional all-oxide heterostructures