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DS: Fachverband Dünne Schichten

DS 12: FePt Nanoparticles (jointly with MA, MM – Organizer: Farle)

DS 12.4: Topical Talk

Montag, 26. März 2012, 16:30–17:00, EB 202

Understanding the Metal-Carbon Interface in FePt terminated carbon nanotubes — •Darius Pohl¹, Franziska Schäffel¹, Christine Täschner¹, Marc H. Rümmeli¹, Christian Kisielowski², Ludwig Schultz¹, and Bernd Rellinghaus¹ — ¹IFW Dresden, P.O. Box 270116, Dresden, D-01171, Germany — ²Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

Plasma-enhanced chemical vapour deposition (PE-CVD) onto FePt catalyst films is used to synthesize carbon nanotubes (CNT) which are teminated with L10-ordered FePt nanomagnets with high magnetic anisotropy [1]. The CNT are characterized by means of low voltage aberration-corrected HRTEM. To gain a deeper insight into the growth mechanism and in order to understand the relative crystallographic orientation of the particles with respect to the CNT axes structural investigations are conducted with a strong focus on the atomically resolved characterisation of the FePt-CNT interface. An interface-near expansion of the metal lattice is observed and attributed to a segregation of Pt towards the surface of the catalyst particle. Detailed statistical HRTEM analyses of these interfaces reveal that the CNT preferentially emanate from {111} facets of the catalyst particle. Molecular dynamic simulations were conducted to estimate the desorption energy of carbon atoms for various surfaces. Our results indicate that the physical principle based upon which the interfacial metal facet is chosen is a reduction of the desorption energy for carbon [2].

[1] F. Schäffel et al., Appl. Phys. Lett. 94 (2009) 193197.

[2] D. Pohl et al., Phys. Rev. Lett. 107 (2011) 185501.