Atomic layer deposition of YMnO3 thin films

Abstract

YMnO3 (YMO) thin films were synthesized by radical-enhanced atomic layer deposition (RE-ALD) on silicon (Si) and yttria-stabilized zirconia (YSZ)substrates, to investigate the effect of film composition and substrates on their intrinsic magnetic properties. The crystalline phase of these ultra-thin films depends on both the processing conditions and the substrate lattice parameters. The Mn/Y atomic ratio of the YMO thin films could be controlled near unity by adjusting the Mn:Y precursor pulsing ratio during the RE-ALD processes. The ALD YMO thin film on Si (111) was orthorhombic, regardless of the film thickness with a Néel temperature (TN) between 48 ∼ 62 K, as determined through the anomalies observed during DC magnetic susceptibility measurements. However, ultra-thin ALD YMO films (∼6 nm) on YSZ (1 1 1), at a Mn/Y atomic ratio near unity, has both orthorhombic- and hexagonal- phases, yielding two TN anomalies measured at ∼48 K and ∼85 K. The induction of magnetization of ultra-thin YMO film on Si (1 1 1) under an in-situ 20 V electric poling indicates that the magnetoelectric coupling was observed below TN, showing that the ALD synthesis could be a promising technique to deposit ultra-thin magnetoelectric films.