Beijing National Laboratory for Condensed Matter & Institute of Physics, Chinese Academy of Sciences , Beijing 100190, People's Republic of China.
College of Physics Science and Technology, Hebei University , Baoding 071002, Hebei Province, People's Republic of China.
ACS Appl Mater Interfaces. 2016 Jul 20;8(28):18328-33. doi: 10.1021/acsami.6b03756. Epub 2016 Jul 11.
Structural and magnetic properties of the LaCoO3/SrTiO3 (LCO/STO) multilayers (MLs) with a fixed STO layer of 4 nm but varied LCO layer thicknesses have been systematically studied. The MLs grown on Sr0.7La0.3Al0.65Ta0.35O3 (LSAT) and SrTiO3 (STO) exhibit the in-plane lattice constant of the substrates, but those on LaAlO3 (LAO) show the in-plane lattice constant between those of the first two kinds of MLs. Compared with the LCO single layer (SL), the magnetic order of the MLs is significantly enhanced, as demonstrated by a very slow decrease, which is fast for the SL, of the Curie temperature and the saturation magnetization as the LCO layer thickness decreases. For example, clear ferromagnetic order is observed in the ML with the LCO layer of ∼1.5 nm, whereas it vanishes below ∼6 nm for the LCO SL. This result is consistent with the observation that the dark stripes, which are believed to be closely related to the magnetic order, remain clear in the MLs while they are vague in the corresponding LCO SL. The present work suggests a novel route to tune the magnetism of perovskite oxide films.
LaCoO3/SrTiO3（LCO/STO）多层膜（MLs）的结构和磁性研究，其中 STO 层厚度固定为 4nm，但 LCO 层厚度不同。在 Sr0.7La0.3Al0.65Ta0.35O3（LSAT）和 SrTiO3（STO）上生长的 MLs 表现出与衬底平面晶格常数相同的性质，但在 LaAlO3（LAO）上生长的 MLs 表现出前两种 MLs 之间的平面晶格常数。与 LCO 单层（SL）相比，MLs 的磁有序显著增强，表现为居里温度和饱和磁化强度随 LCO 层厚度的减小而缓慢下降，而对于 SL 则快速下降。例如，在 LCO 层约为 1.5nm 的 ML 中观察到清晰的铁磁有序，而在 LCO SL 中，当 LCO 层厚度小于约 6nm 时，铁磁有序消失。这一结果与观察到的结果一致，即认为与磁有序密切相关的暗条纹在 MLs 中保持清晰，而在相应的 LCO SL 中则变得模糊。本工作为调制钙钛矿氧化物薄膜的磁性提供了一种新途径。
