Berlin 2012 – scientific programme

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MA: Fachverband Magnetismus

MA 1: Joint Symposium "Tailoring Magnetism in L1₀-ordered Nanostructures: Perspectives for Magnetic Recording beyond 1 Tb/in²" (SYTM)

MA 1.2: Invited Talk

Monday, March 26, 2012, 10:00–10:30, H 0105

Large-area hard magnetic L1₀-FePt and composite L1₀-FePt based nanopatterns — •Dagmar Goll¹ and Thomas Bublat² — ¹Hochschule Aalen, Institut für Materialforschung, Aalen — ²Max-Planck-Institut für Intelligente Systeme, Stuttgart

Bit-patterned media is a very promising concept for next generation ultrahigh density magnetic recording. Large-area hard magnetic L1₀-FePt based nanopatterns with dot sizes between 40 nm and 100 nm and out-of-plane texture were fabricated by using a top-down approach [1,2]. For the fabrication process ultraviolet nanoimprint lithography in combination with inductively coupled plasma reactive Ar-ion etching has been used. By this technique continuous epitaxially grown L1₀-FePt films were nanostructured into a regular arrangement of nanodots over an area of 4 mm². In the as-etched state the morphology of the dots corresponds to the morphology of phase graded L1₀-FePt/A₁-FePt composite particles with coercivities up to 1.7 T at RT. After post-annealing the morphology of the dots is of pure L1₀-FePt resulting in coercivities up to 4.4 T. Within the framework of micromagnetism the magnetic reversal mechanism of the different types of nanodots has been analyzed from the temperature dependence and angular dependence of the reversal field. For the as-etched dots magnetization reversal takes place by a domain wall induced process and for the post-annealed dots by a uniform nucleation process. Additionally composite L1₀-FePt/Fe nanopatterns were produced from continuous bilayers and characterized. [1] T. Bublat, D. Goll, Nanotechnology 22 (2011) 315301. [2] T. Bublat, D. Goll, J. Appl. Phys. 110 (2011) 073908.