Out-of-Plane Magnetic Patterning Based on Indentation-Induced Nanocrystallization of a Metallic Glass

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 6; no. 14; pp. 1543 - 1549
• Main Authors: Sort, Jordi, Bonavina, Luiz Fernando, Varea, Aïda, Souza, Carlos, Botta, Walter J., Kiminami, Claudio S., Bolfarini, Claudemiro, Suriñach, Santiago, Baró, Maria Dolors, Nogués, Josep
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 19.07.2010; WILEY‐VCH Verlag
• Subjects: Amorphous materials; Crystallization; Ferromagnetism; Glass; glasses; Magnetic anisotropy; Magnetics; Metallic glasses; metallic materials; Metals; Nanocrystals; Nanoindentation; Nanostructures; patterning; Surface layer; Texture
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.201000510

Periodic arrays of micrometer‐sized ferromagnetic structures with perpendicular magnetic anisotropy are prepared by nanoindentation at the surface of a Fe67.7B20Cr12Nb0.3 glassy ribbon initially showing in‐plane magnetic anisotropy. The indented regions exhibit enhanced coercivity and saturation magnetization with respect to the surrounding nondeformed matrix. These effects are due to a mechanically driven selective nanocrystallization of the metallic glass, induced by nanoindentation, even without the need for thermal annealing. In addition, while the amorphous matrix becomes paramagnetic above 325 K, the crystallized regions (consisting of α‐Fe) remain ferromagnetic upon heating to high temperatures. The local change in the magnetic anisotropy direction is ascribed to a certain degree of crystallographic texture, together with the inverse magnetostriction effect caused by the compressive indentation stresses. Arrays of micrometer‐sized magnetic structures with perpendicular anisotropy are prepared by nanoindentation of a glassy ribbon with in‐plane magnetic anisotropy. Nanoindentation causes nanocrystallization of α‐Fe in the glass, which results in larger magnetization and Curie temperature than those of the amorphous matrix. The change in the anisotropy direction is ascribed to crystallographic texture and inverse magnetostriction effects.