Due to the strong interlayer coupling between multiple degrees of freedom, oxide heterostructures usually produce distinct interfacial phases with unexpected functionalities. Here, we report on the realization of quasi-two-dimensional ferromagnetic state in ultrathin La0.7Sr0.3MnO3 (LSMO) layer down to two unit cells (u.c.), being sandwiched by the planar infinite-layer structured SrCuO2 layers (P-SCO). We find the LSMO/P-SCO interface coupling has greatly suppressed the magnetic dead layer of LSMO, resulting in an emergent interfacial ferromagnetic phase. Thus, robust ferromagnetic order can be maintained in the 2 u.c.-thick LSMO layer (∼7.7 Å), showing a Curie temperature of ∼260 K and remarkable perpendicular magnetic anisotropy. X-ray absorption spectra reveal notable charge transfer from Mn to Cu at the interface, and thus, resulted preferential d3z2−r2 orbital occupation for interfacial Mn ions plays an important role in the inducing of perpendicular magnetic anisotropy in quasi-two-dimensional LSMO layer. Our work demonstrates a unique approach for tuning the properties of oxides via an interface engineering of oxygen coordination in perovskite/infinite-layer heterostructures.

中文翻译：

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La0.7Sr0.3MnO3/SrCuO2 界面处出现具有垂直磁各向异性的准二维铁磁态

由于多个自由度之间的强层间耦合，氧化物异质结构通常产生具有意想不到的功能的不同界面相。在这里，我们报告了在超薄 La0.7Sr0.3MnO3 (LSMO) 层中实现准二维铁磁态，直至两个晶胞 (uc)，夹在平面无限层结构 SrCuO2 层 (P-SCO ）。我们发现LSMO/P-SCO界面耦合极大地抑制了LSMO的磁死层，导致界面铁磁相的出现。因此，在 2 uc 厚的 LSMO 层（~7.7 Å）中可以保持鲁棒的铁磁有序，表现出~260 K 的居里温度和显着的垂直磁各向异性。 X射线吸收光谱显示界面处从Mn到Cu的显着电荷转移，因此，界面Mn离子的优先d3z2−r2轨道占据在准二维LSMO层中诱导垂直磁各向异性中起着重要作用。我们的工作展示了一种通过钙钛矿/无限层异质结构中氧配位的界面工程来调节氧化物性能的独特方法。