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0966-T03-01

Magnetic and Ferroelectric Properties of YMnO3 Epitaxial Thin Films Kazuhiro Maeda, Takeshi Yshimura, and Norifumi Fujimura Osaka Prefecture University, Sakai, Japan

ABSTRACT YMnO3, which is one of hexagonal RMnO3 compounds, has antiferromagnetic (AFM) and ferroelectric properties, simultaneously. Recently, it has been reported that cross-correlation in the magnetic dielectric properties on hexagonal YMnO3 single crystals. However, the crosscorrelation in the magnetic-ferroelectric properties has not been understood yet. In this study, we investigated the cross correlation between magnetism and ferroelectricity on YMnO3 epitaxial films with excellent crystallinity. YMnO3 epitaxial films were deposited pulsed laser deposition. The YMnO3 epitaxial films show the dielectric anomalies at around Néel point of the films. It was suggested that the ferroelectric domain switching was suppressed by the magnetic ordering. The relationship between the magnetic structure and the ferroelectric properties are discussed in terms of the temperature dependences of magnetization and dielectric permittivity. Moreover, the ablation plume of YMnO3 was investigated by optical emission spectroscopy. The effect of the ablation conditions on the thin film growth and electrical properties was discussed. INTRODUCTION Material group called multiferroics has attracted considerable attention. Multiferroics have multiple properties simultaneously such as ferroelectricitiy, ferromagnetism, ferroelasticity and shows cross-correlation among the properties. [1-7] This kind of multiferroic property should be attractive as novel computing with non-volatile effect. We have studied on YMnO3, which is one of hexagonal RMnO3 compounds and has AFM and ferroelectric properties, simultaneously. [2] In hexagonal RMnO3, each magnetic Mn3+ ion is surrounded by five oxygen ions, forming a corner-shared MnO5 bipyramid. RMnO3 shows ferroelectricity along c axis due to the tilting of MnO5 briyrmaid and the change of distance between oxygen and rare-earth ions. [6] Moreover, Below Néel point ~70K, hexagonal RMnO3 shows antiferromagnetism by the magnetic ordering of Mn3+. Recently, it has been reported the cross-correlation in the magnetic-dielectric properties on hexagonal RMnO3 single crystals including YMnO3. [2] In single crystals of YMnO3 and LuMnO3, the dielectric permittivity largely reduced below the AFM Néel point. We examined the relationship between the ferroelectric domain switching and the ordering of magnetic moment using YMnO3 epitaxial films deposited by pulsed laser deposition method. [8-10] EXPERIMENT YMnO3 thin films with a thickness of 100 nm were deposited using pulsed laser deposition method. In this method, sintered ceramics are used as a target in many cases and the quality of the target has an important influence on the quality of the deposited thin films. In this study, to

obtain targets with high density, the ceramic bulk of YMnO3 was prepared by the following process. Y2O3 (99.9%) and Mn3O4 (99.9%) were mixed in a ratio of 3: