Shi Wenxiao, Zhang Jing, Yu Bowen, Zheng Jie, Wang Mengqin, Li Zhe, Zheng Jingying, Liu Banggui, Chen Yunzhong, Hu Fengxia, Shen Baogen, Chen Yuansha, Sun Jirong
Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, China.
School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
Nat Commun. 2024 Nov 15;15(1):9931. doi: 10.1038/s41467-024-54311-0.
Artificial oxide heterostructures have provided promising platforms for the exploration of emergent quantum phases with extraordinary properties. Here, we demonstrate an approach to stabilize a distinct oxygen octahedron rotation (OOR) characterized by in the ultrathin LaNiO sublayers of the LaNiO/CaTiO superlattices. Unlike the OOR in the LaNiO bare film, the OOR favors high conductivity, driving the LaNiO sublayer to a metallic state of ~100 K even when the layer thickness is as thin as 2 unit cells (u.c.). Simultaneously, strongly preferred occupation of orbital is achieved in LaNiO sublayers. The largest change of occupancy is as high as 35%, observed in the 2 u.c.-thick LaNiO sublayers sandwiched between 4 u.c.-thick CaTiO sublayers. X-ray absorption spectra indicate that the OOR pattern of LaNiO achieved in the LaNiO/CaTiO heterostructures has significantly enhanced the Ni-3d/O-2p hybridization, stabilizing the metallic phase in ultrathin LaNiO sublayers. The present work demonstrates that modulating the mode of OOR through heteroepitaxial synthesis can modify the orbital-lattice correlations in correlated perovskite oxides, revealing hidden properties of the materials.
人工氧化物异质结构为探索具有非凡特性的新兴量子相提供了有前景的平台。在此，我们展示了一种方法，可在LaNiO/CaTiO超晶格的超薄LaNiO子层中稳定一种以 为特征的独特氧八面体旋转（OOR）。与LaNiO裸膜中的 OOR不同， OOR有利于高电导率，即使层厚度薄至2个晶胞（u.c.），也能将LaNiO子层驱动到约100 K的金属态。同时，在LaNiO子层中实现了 轨道的强烈优先占据。在夹在4 u.c.厚的CaTiO子层之间的2 u.c.厚的LaNiO子层中观察到，占据率的最大变化高达35%。X射线吸收光谱表明，在LaNiO/CaTiO异质结构中实现的LaNiO的 OOR模式显著增强了Ni-3d/O-2p杂化，稳定了超薄LaNiO子层中的金属相。目前的工作表明，通过异质外延合成调节OOR模式可以改变相关钙钛矿氧化物中的轨道-晶格相关性，揭示材料的隐藏特性。
