Interface Effects on Magnetic Anisotropy and Domain Wall Depinning Fields in Pt/Co/AlO_x Thin Films

Abstract

We report the dependence of the domain wall depinning field, domain wall velocity, including anisotropy direction, and magnetic properties on the oxidized aluminum thickness of perpendicularly magnetized asymmetric Pt/Co/AlOx trilayers. We also adopt the low-temperature magneto-transport measurement technique to investigate the amount of oxygen at the Co/AlOx interface of our magnetic thin films. At the lowest temperature of 25 K, it is found that the coercivity for the 5 nm aluminum thickness sample is very close to the average value and coercivity diminished above and below this critical aluminum thickness, hinting at a large variation in CoOx content at the interface. This tendency is also consistent with the modification of the depinning fields, coercive fields, and surface roughness measured at room temperature. Our results highlight an efficient way of controlling the depinning fields and other magnetic characteristics, which is important for stabilizing and driving magnetic spin textures and applicable to energy-efficient next-generation spintronics devices.

Keywords

• interface
• domain walls
• perpendicular magnetic anisotropy
• magneto-optical Kerr effect
• depinning field
• skyrmion