Strong Interfacial Perpendicular Magnetic Anisotropy in Exchange-Biased NiO/Co/Au and NiO/Co/NiO Layered Systems

Area of Science:

• Spintronics
• Materials Science
• Condensed Matter Physics

Background:

• Perpendicular magnetic anisotropy (PMA) is crucial for advanced spintronic devices.
• Antiferromagnetic oxides (AFOs) offer new functionalities via exchange bias (EB) coupling.
• Investigating NiO/Co interfaces explores PMA and EB for novel applications.

Purpose of the Study:

• To investigate PMA and EB effects in NiO/Co/Au and NiO/Co/NiO layered systems.
• To understand the influence of NiO layer configuration on magnetic properties.
• To explore methods for controlling magnetic anisotropy and exchange bias.

Main Methods:

• Fabrication and characterization of NiO/Co/Au and NiO/Co/NiO layered structures.
• Magnetic property measurements, including coercive field and EB field.
• Analysis of PMA contributions and effects of thermal annealing.
• Application of field cooling processes for EB control.

Main Results:

• Coercive and EB fields significantly increase when the Co layer is sandwiched between two NiO layers.
• Strong PMA is achieved without a heavy metal/ferromagnetic interface by surrounding Co with NiO.
• PMA originates from a substantial surface contribution (0.74 mJ/m²), enhanced to 0.99 mJ/m² upon annealing (~450 K).
• Field cooling enables wide-ranging control of the EB field without affecting other key magnetic properties.

Conclusions:

• Sandwiching Co layers with NiO significantly enhances PMA and EB.
• NiO/Co/NiO structures provide a route to out-of-plane magnetization without heavy metals.
• Annealing and field cooling offer tunable control over magnetic properties for spintronic applications.