Dresden 2006 – wissenschaftliches Programm

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MA: Magnetismus

MA 24: Magnetic Thin Films III

MA 24.5: Vortrag

Donnerstag, 30. März 2006, 11:15–11:30, HSZ 03

Structure and magnetism of epitaxial HoMnO₃ films grown by pulsed laser deposition — •J.-W. Kim, K. Dörr, K. Nenkov, and L. Schultz — IFW-Dresden, PB 270116, 01171 Dresden

Hexagonal HoMnO₃ is one of the most studied multiferroic materials. It is ferroelectric below Curie temperature of T_C 860K and antiferromagnetic below Néel temperature of T_N 76K. Some experiments have been done with HoMnO₃ bulk crystals to reveal strong magneto-electric coupling, even switching to ferromagnetic order of Ho³⁺ spins by an applied electric field [1]. To our knowledge, no epitaxial HoMnO₃ film has been made so far.

We have tried to grow epitaxial hexagonal HoMnO₃ films by pulsed laser deposition on Y-stabilized ZrO₂ (111) substrates. The optimum deposition temperature was 850^oC and oxygen pressure was 1x10⁻¹mbar. We found that lower oxygen pressure disturbs the proper hexagonal phase growth. A beautiful crystallinity of untwined, epitaxially grown HoMnO₃ films was found by X-ray diffraction and pole figure measurement. Low temperature SQUID measurements (down to 1.7K) show some magnetic anomalies in dependence on temperature and applied magnetic field below 6K. These might be related to Ho³⁺ spin ordering and/or reorientation.

The author, J.-W. Kim, thanks to Deutscher Akademischer Austausch Dienst(DAAD) for a fellowship.

[1] Th. Lottermoser, Nature 430 (2004), 541-544