Iron oxidation, interfacial expansion, and buckling at the Fe/NiO(001) interface

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Exchange bias in metal/magnetic-oxide interfaces is crucial for spintronic devices.
• Understanding interfacial structures is key to controlling magnetic properties.

Purpose of the Study:

• To provide a structural basis for understanding exchange bias at the Fe/NiO(001) interface.
• To elucidate the atomic arrangement and chemical states at the interface.

Main Methods:

• X-ray absorption spectroscopy (XAS) for elemental and chemical state analysis.
• Ab initio density functional theory (DFT) calculations for structural and magnetic property simulations.

Main Results:

• An interfacial FeO planar layer with a 7% expanded interlayer distance and 0.3 Å buckling was identified.
• A Fe-Ni alloyed phase was observed on top of the FeO layer.
• The FeO layer is predicted to enhance the spin magnetic moment of interface Fe atoms by 0.6 μB.

Conclusions:

• The determined interface structure provides insights into the physical mechanisms of exchange bias.
• The presence of the FeO layer and alloyed phase significantly influences interfacial magnetism.