Regensburg 2004 – wissenschaftliches Programm

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MA: Magnetismus

MA 20: Magnetische dünne Schichten II

MA 20.10: Vortrag

Donnerstag, 11. März 2004, 12:30–12:45, H10

Sr₂FeMoO₆ Thin Film Preparation, Properties and Prospects — •Nicole Auth¹, Diana Sanchez², and Gerhard Jakob¹ — ¹Johannes Gutenberg Universität, Mainz — ²Instituto de Ciencia de Materiales de Madrid, CSIC

Since the first report of room temperature magneto-resistance in polycrystalline Sr₂MoFeO₆ (SFMO) this double-perovskite material has been widely studied. Due to its high Curie temperature of 420 K and band structure calculations predicting 100% spin polarisation, SFMO is a potential candidate for spintronic devices. Yet most studies are concerned with bulk material while the preparation of good quality thin films has proven to be a non-trivial task.

We prepared epitaxial thin films of SFMO on SrTiO₃ (100) substrates by pulsed laser deposition. Differing from previous reports a post-deposition annealing step in vacuum with a low oxygen partial pressure was introduced. The structural, magnetic and transport properties are studied in detail. We also investigated film growth on a Ba_0.4Sr_0.6TiO₃ (BST) buffer layer and on DyScO₃ substrates. Both types of seed crystals offer a nearly perfect lattice match for the formation of the SFMO thin film. While the DyScO₃ substrate has a perfect c-axis orientation the BST buffer layer exhibits a large angular spread of the crystallites leading to a clear change in the magneto-transport properties.

We succeeded in growing samples with comparably smooth surface as a prerequisite for multilayer preparation. For studying the TMR effect we are working on nanoscale patterning of mesa-structures by a combination of photolithography, focussed ion beam etching and e-beam lithography.