Berlin 2015 – scientific programme
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MA: Fachverband Magnetismus
MA 38: Magnetic Nanoparticles
MA 38.1: Talk
Thursday, March 19, 2015, 09:30–09:45, H 0110
Tuning the magnetic properties of granular FePt media by seed layer conditioning — •S. Wicht1,2, V. Neu1, L. Schultz1,2, O. Mosendz3, V. Mehta3, S. Jain3, J. Reiner3, O. Hellwig3, D. Weller3, and B. Rellinghaus1 — 1IFW Dresden, Hemholtzstr. 20, D-01069 Dresden, Germany — 2TU Dresden, IFWW, D-0162 Dresden, Germany — 3HGST, 3403 Yerba Buena Rd, San Jose, CA-95135, USA.
In the course of the steadily increasing amount of digitized information reliable data storage at ultimate storage densities is mandatory. Accordingly, areal densities in future storage media will soon cross the 1 TB/in2 border. For such media, L10 ordered, granular FePt-X films, grown on highly textured MgO, are promising materials candidates. The present work aims at a better understanding of the influence of the MgO seed layer roughness on the structure and the magnetic performance of the granular media. Therefore, the MgO was subjected to Ar+ ion irradiation prior to the deposition of the magnetic material. Aberration-corrected high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometry (VSM) are used to correlate the structure with the magnetic properties. We find that decreasing the surface roughness of the oxide seed layer results in a change of the morphology of the grains from spherical over cylindrical to island-type shapes. This modification is accompanied by an enhanced fraction of small second layer particles and an increasing degree of coalescences of the primarily deposited grains. Concerning the magnetic properties, this results in a reduction of the coercivity from 5 to 2.6 T.