Dresden 2006 – scientific programme

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MA: Magnetismus

MA 20: Poster: Films(1-36) Transp(37-56) Ex.Bias(57-67) Spindyn(68-80) Micromag(81-95) Particle(96-109) Imag.+Surface(110-113) Spinelectr(114-122) Theory+Micromag(123-131) Spinstr+Aniso(132-142) MagMat(143-156) Meas(157,158) MolMag+Kondo(159-162) Postdead(163-)

MA 20.107: Poster

Tuesday, March 28, 2006, 15:15–19:15, P1

Preparation of Homogeneous Arrays of fct FePt Nanoparticles Using a Micellar Approach — •Birgit Kern, Ulf Wiedwald, Luyang Han, Frank Weigl, Hans-Gerd Boyen, and Paul Ziemann — Abteilung Festkörperphysik, Universität Ulm, Albert-Einstein-Allee 11, D-89069 Ulm, Germany

Within the last years worldwide efforts have been directed towards the preparation of fct FePt nanoparticlate systems due to their huge magnetic anisotropy energy promising applications in data storage technology. The so-called colloidal approach represents a simple, cost-efficient method to prepare highly ordered arrays of such FePt nanoparticles. It turns out, however, that the FePt particles natively show the fcc phase and have to be annealed at 600-800^∘C to achieve the magnetically appealing fct phase. Such a heat treatment, however, is likely to result in the formation of larger agglomerates due to very small interparticle distances of about 2-3 nm. Here, we present an alternative method to prepare ordered arrays of well-separated and chemically pure FePt alloy particles with diameters of 3-10 nm and interparticle distances of 20-100 nm. These nanomagnets are synthesized by exploiting the selforganization of metal salt-loaded diblock copolymer reverse micelles, followed by plasma-aided removal of the polymer matrix after deposition of the loaded micelles onto native Si substrates. Although the micellar approach yields FePt particles in the low-anisotropy fcc phase as well, the subsequent annealing step towards the fct phase at 700^∘C can safely be performed without any agglomeration of particles or loss of the array quality.