Engineering Magnetic Anisotropy in Permalloy Films via Atomic Force Nanolithography

Atomic force nanolithography provides a precise method for sculpting magnetic thin films, enabling controlled engineering of magnetic anisotropy in soft ferromagnets at the microscale. We demonstrate that nanoscale groove arrays patterned into permalloy ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msub><mml:mi>Ni</mml:mi> <mml:mn>80</mml:mn></mml:msub> <mml:msub><mml:mi>Fe</mml:mi> <mml:mn>20</mml:mn></mml:msub> </mml:mrow> <mml:annotation>${\rm Ni}_{80}{\rm Fe}_{20}$</mml:annotation></mml:semantics> </mml:math> ) films induce a robust in-plane uniaxial anisotropy, with the easy axis aligned along the groove direction. The effective anisotropy field is shown to increase with decreasing groove period and increasing engraving depth, offering continuous tunability of magnetic hardness within a single fabrication step. Artificially engraved microstructures further allow domain configurations and domain-wall trajectories to be directed along predefined pathways, exemplified by the creation of a chessboard-like magnetic landscape. Owing to its adaptability to diverse ferromagnetic materials and arbitrary corrugation geometries, this approach provides a versatile platform for tailoring in-plane magnetic anisotropy. Concrete applications are demonstrated in the design of magnonic elements and anisotropic magnetoresistance sensors.