ABSTRACTThe successful preparation of fully epitaxial spin-valves elaborated on NiO(111) single crystals is reported. The growth conditions of a smooth 2D permalloy (Py = Ni80Fe20) layer have been determined. A very strong magnetic exchange interaction is evidenced on the Py/NiO(111) interface. It strongly modifies the magnetic properties of Py that acquires high coercivity, leaving it as a hard magnetic material. The second Py layer has unchanged magnetic properties and plays the role of the sensing soft magnetic layer. A giant magnetoresistance (GMR) of 3.5% at room temperature was easily obtained without optimizing the thickness of the different layers. Complementarily energy-filtered (EF-) and high-resolution (HR-) transmission electron microscopy (TEM) were used to fully characterize the spin valves. Within the framework of magnetic exchange coupling, our results open the possibility to elaborate model spin valves in which the role of each interface can be investigated and controlled at the atomic level. The detrimental effect of an inter-diffusion at the Py/NiO interface is evidenced.