Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 32: Postersession II: Spinstruct./Phase Trans. (1-10); Spinelectronics (11-15); Thin Films (16 - 36); Particles/Clusters (37-45); Multiferroics (46-54); Spindynamics/Spin Torque (55 - 76); Post Deadlines (77-79)

MA 32.54: Poster

Friday, February 29, 2008, 11:15–14:00, Poster E

Structure and magnetism of multiferroic hexagonal HoMnO₃ — •Jong-Woo Kim¹, Kathrin Dörr¹, Konstantin Nenkov¹, Ludwig Schultz¹, Bas B. van Aken², and Manfred Fiebig² — ¹Institute for Metallic Materials, IFW, Dresden, Germany — ²HISKP, Universität Bonn, Germany

Multiferroics which show more than two ferroic orders simultaneously in the same phase have got considerable attention recently due to their academic and industrial significance. Among the candidates, hexagonal HoMnO₃ has been revealed as most promising single-phase multiferroics for its strong magnetoelectric effect [1,2]. We have grown twin-free epitaxial HoMnO₃ films of thicknesses from 25 nm to 1 µm on (111) Y:ZrO₂ (YSZ) substrates by pulsed laser deposition (PLD). Magnetization measurements reveal several anomalies related with magnetic Ho ordering in the magnetic field vs temperature phase diagram. These anomalies differ in details from those of single crystals, possibly due to the effect of epitaxial strain. We depict a rough phase diagram of both a HoMnO₃ film and a single crystal. With non-linear optics (second harmonic generation), the ferroelectric polar order of the films has been observed [3]. For the investigation of magnetoelectric properties, trilayer capacitor structures using an epitaxial Pt bottom electrode have been prepared. The electric polarization measurements show ferroelectric switching at 300 K.

[1] F. Yen, et al., Phys. Rev. B 71, 180407 (2005)

[2] T. Lottermoser, et al., Nature 430, 541 (2004)

[3] J.-W. Kim et al., Appl. Phys. Lett. 90, 012502 (2007)