NdNiO$_3$/CaMnO$_3$界面处协同双交换和超交换驱动的双亚晶格铁磁性

中文摘要 AI 辅助

在关联氧化物界面工程化涌现铁磁性为创造母体材料中不存在的集体态提供了强大途径。在此，我们展示了NdNiO$_3$/CaMnO$_3$超晶格中的界面价态重构产生了涉及Mn和Ni的双亚晶格铁磁性。深度分辨的驻波X射线光电子能谱揭示了CaMnO$_3$侧界面处增强的Mn$^{3+}$特征和NdNiO$_3$侧增强的Ni$^{2+}$特征，分别确立了Mn$^{4+}$-O-Mn$^{3+}$双交换和Ni$^{2+}$-O-Mn$^{4+}$超交换所需的构型。在低温下，元素特异性XMCD揭示了两个亚晶格的铁磁响应，其中Ni响应主要集中于Ni$^{2+}$衍生的光谱分量，而SW-XPS独立显示该分量在界面处增强。总之，这些结果表明CaMnO$_3$内的协同双交换和跨界面的超交换耦合了Mn和Ni亚晶格，为在关联氧化物中工程化界面铁磁性提供了一种通用策略。

英文摘要

Engineering emergent ferromagnetism at correlated-oxide interfaces offers a powerful route to creating collective states that do not exist in the parent materials. Here, we show that interfacial valence reconstruction in NdNiO$_3$/CaMnO$_3$ superlattices generates dual-sublattice ferromagnetism involving both Mn and Ni. Depth-resolved standing-wave X-ray photoelectron spectroscopy reveals enhanced Mn$^{3+}$ character on the CaMnO$_3$ side of the interface and enhanced Ni$^{2+}$ character on the NdNiO$_3$ side, establishing the configurations required for Mn$^{4+}$-O-Mn$^{3+}$ double exchange and Ni$^{2+}$-O-Mn$^{4+}$ superexchange, respectively. At low temperature, element-specific XMCD reveals ferromagnetic responses from both sublattices, with the Ni response concentrated predominantly in the Ni$^{2+}$-derived spectral component that SW-XPS independently shows to be enhanced at the interface. Together, these results show that cooperative double exchange within CaMnO$_3$ and superexchange across the interface couple the Mn and Ni sublattices, providing a general strategy for engineering interfacial ferromagnetism in correlated oxides.

发表机构

• Temple University（天普大学）
• Rutgers University（罗格斯大学）
• Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）
• Diamond Light Source Ltd.（钻石光源有限公司）

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