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Abstract：
The hexagonal ferrite h-YbFeO3 grown on YSZ(111) by pulsed laser deposition is foreseen as a promising single multiferroic candidate where ferroelectricity and antiferromagnetism coexist for future applications at low temperatures. We studied in detail the microstructure as well as the temperature dependence of the magnetic properties of the devices by comparing the heterostructures grown directly on YSZ(111) (i.e., YbPt_Th0nm) with h-YbFeO3 films deposited on substrates buffered with platinum Pt/YSZ(111) and in dependence on the Pt underlayer film thickness (i.e., YbPt_Th10nm, YbPt_Th40nm, YbPt_Th55nm, and YbPt_Th70nm). The goal was to deeply understand the importance of the crystal quality and morphology of the Pt underlayer for the h-YbFeO3 layer crystal quality, surface morphology, and the resulting physical properties. We demonstrate the relevance of homogeneity, continuity, and hillock formation of the Pt layer for the h-YbFeO3 microstructure in terms of crystal structure, mosaicity, grain boundaries, and defect distribution. The findings of transmission electron microscopy and X-ray diffraction reciprocal space mapping characterization enable us to conclude that an optimum film thickness for the Pt bottom electrode is ThPt = 70 nm, which improves the crystal quality of h-YbFeO3 films grown on Pt-buffered YSZ(111) in comparison with h-YbFeO3 films grown on YSZ(111) (i.e., YbPt_Th0nm). The latter shows a disturbance in the crystal structure, in the up-and-down atomic arrangement of the ferroelectric domains, as well as in the Yb-Fe exchange interactions. Therefore, an enhancement in the remanent and in the total magnetization was obtained at low temperatures below 50 K for h-YbFeO3 films deposited on Pt-buffered substrates Pt/YSZ(111) when the Pt underlayer reached ThPt = 70 nm.
摘要：
通过脉冲激光沉积在YSZ（111）上生长的六方铁氧体h-YbFeO3被认为是一种有前途的单一多铁性候选物，其中铁电性和反铁磁性共存，可在低温下应用。我们通过比较直接在YSZ（111）上生长的异质结构（即，YbPt_Th0nm）与h-YbFeO3膜沉积在用铂Pt/YSZ（111）缓冲的衬底上，并取决于Pt下层膜厚度（即，YbPt_Th10nm,YbPt_Th40nm,YbPt_Th55nm,和YbPt_Th70nm)。目的是深入了解Pt底层的晶体质量和形态对h-YbFeO3层晶体质量的重要性，表面形态,以及由此产生的物理性质。我们证明了同质性的相关性，连续性,在晶体结构方面，h-YbFeO3微观结构的Pt层的小丘形成，马赛克，晶界,和缺陷分布。透射电子显微镜和X射线衍射倒数空间映射表征的发现使我们能够得出结论，Pt底部电极的最佳膜厚度为ThPt=70nm，与在YSZ（111）上生长的h-YbFeO3薄膜相比，提高了在Pt缓冲的YSZ（111）上生长的h-YbFeO3薄膜的晶体质量（即，YbPt_Th0nm)。后者显示出晶体结构中的干扰，在铁电畴的上下原子排列中，以及在Yb-Fe交换相互作用中。因此,当Pt底层达到ThPt=70nm时，在低于50K的低温下，沉积在Pt缓冲衬底Pt/YSZ（111）上的h-YbFeO3薄膜的剩磁和总磁化强度得到了增强。
