Interface-Engineered Magnetic Anisotropy in Zigzag Nanostructured Thin Films.

Precise control of uniaxial magnetic anisotropy (UMA) in thin films is essential for next-generation spintronic devices and magnetic sensors. While conventional oblique-angle deposition (OAD) engineers this anisotropy via tilted columnar nanostructures, it is fundamentally limited by morphological instabilities at larger thicknesses. The present study utilises sequential oblique-angle deposition (S-OAD), which overcomes these limitations by fabricating zigzag nanostructures that prevent column merging and introduce periodically repeated high-density interfaces. In this study, the precise influence of these engineered interfaces on macroscopic magnetic behaviour has been systematically studied by increasing the number of zigzag bilayers. An unusual anisotropy crossover in zigzag cobalt (Co) films is observed with increasing bilayer number, which led us to identify a novel magnetic anisotropy component: an interface-induced shape anisotropy originating from the high-density junctions (interfaces) between oppositely tilted columns, which competes with texture-driven magnetocrystalline anisotropy (MCA) of Co. The universality of this interface-driven mechanism is further validated in Heusler alloy Co2FeAl films, where strong UMA is achieved despite intrinsically weak MCA. These findings establish S-OAD as a platform that introduces interfaces as a new structural degree of freedom, providing a versatile route for precise tuning of UMA in nanostructured multilayers for spintronic applications.