Dresden 2009 – scientific programme

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MA: Fachverband Magnetismus

MA 40: Poster II: Bio- and Molecular Magnetism (1-9); Magnetic Coupling Phenomena/Exchange Bias (10-15); Magnetic Particlicles and Clusters (16-29); Micro and Nanostructured Magnetic Materials (30-51); Multiferroics (52-64); Spin Injection in Heterostructures (65-67); Spin-Dyn./Spin-Torque (68-93); Spindependent Transport (94-108)

MA 40.33: Poster

Friday, March 27, 2009, 11:00–14:00, P1A

Competition of Shape and Magnetocrystalline Anisotropies in Electrodeposited Co Nanowires — Ajeet K. Srivastav^1,2, •Heike Schlörb¹, Sebastian Fähler¹, and Ludwig Schultz¹ — ¹IFW Dresden, Germany — ²IIT Kanpur, India

Ordered arrays of magnetic nanowires are of high interest for both fundamental understanding of magnetism in low dimensions as well as many applications ranging from biological, chemical to information storage systems. They allow studying unexpected effects of different magnetic anisotropies and magnetostatic interactions. Cobalt nanowires are expected to show a complex behaviour due to its hexagonal structure and the resulting high magnetocrystalline anisotropy. Cobalt nanowires were electrodeposited into AAO templates using a single sulphate electrolyte partly buffered by boric acid. The influence of different pH values on structure and temperature dependent magnetic properties was investigated. At high pH and room temperature the easy axis is aligned parallel to the wire axis as expected for high aspect ratio nanowires due to shape anisotropy. Competing effects of shape and magnetocrystalline anisotropies result in a nearly isotropic behaviour at low pH values, when the hexagonal c-axis is oriented perpendicular to the wire axis. Due to the strong temperature dependency of the magnetocrystalline anisotropy the easy magnetization direction in Co nanowires changes from parallel to perpendicular to the wire axis when decreasing temperature. The crossover temperature strongly depends on electrolyte pH indicating changes in both fraction and orientation of the hexagonal phase when pH is increased.