Improved conduction and orbital polarization in ultrathin LaNiO3 sublayer by modulating octahedron rotation in LaNiO3/CaTiO3 superlattices
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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>+</mml:mo></mml:mrow> </mml:msup> </mml:math> in the ultrathin LaNiO<sub>3</sub> sublayers of the LaNiO<sub>3</sub>/CaTiO<sub>3</sub> superlattices. Unlike the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> </mml:math> OOR in the LaNiO<sub>3</sub> bare film, the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>+</mml:mo></mml:mrow> </mml:msup> </mml:math> OOR favors high conductivity, driving the LaNiO<sub>3</sub> 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mrow><mml:mi>d</mml:mi></mml:mrow> <mml:mrow> <mml:msup><mml:mrow><mml:mi>x</mml:mi></mml:mrow> <mml:mrow><mml:mn>2</mml:mn></mml:mrow> </mml:msup> <mml:mo>-</mml:mo> <mml:msup><mml:mrow><mml:mi>y</mml:mi></mml:mrow> <mml:mrow><mml:mn>2</mml:mn></mml:mrow> </mml:msup> </mml:mrow> </mml:msub> </mml:math> orbital is achieved in LaNiO<sub>3</sub> sublayers. The largest change of occupancy is as high as 35%, observed in the 2 u.c.-thick LaNiO<sub>3</sub> sublayers sandwiched between 4 u.c.-thick CaTiO<sub>3</sub> sublayers. X-ray absorption spectra indicate that the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>a</mml:mi></mml:mrow> <mml:mrow><mml:mo>-</mml:mo></mml:mrow> </mml:msup> <mml:msup><mml:mrow><mml:mi>c</mml:mi></mml:mrow> <mml:mrow><mml:mo>+</mml:mo></mml:mrow> </mml:msup> </mml:math> OOR pattern of LaNiO<sub>3</sub> achieved in the LaNiO<sub>3</sub>/CaTiO<sub>3</sub> heterostructures has significantly enhanced the Ni-3d/O-2p hybridization, stabilizing the metallic phase in ultrathin LaNiO<sub>3</sub> 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.
Authors
- Jirong Sun (ORCID: https://orcid.org/0000-0003-4531-4794)
- Bang‐Gui Liu (ORCID: https://orcid.org/0000-0002-6030-6680)
- Fengxia Hu (ORCID: https://orcid.org/0000-0003-0383-0213)
- Baogen Shen (ORCID: https://orcid.org/0000-0003-4819-1806)
- Jingying Zheng (ORCID: https://orcid.org/0009-0003-2003-2499)
- Wenxiao Shi (ORCID: https://orcid.org/0000-0001-9683-1316)
- Yuansha Chen (ORCID: https://orcid.org/0000-0002-7291-5088)
- Yunzhong Chen (ORCID: https://orcid.org/0000-0001-8368-5823)
- Mengqin Wang (ORCID: https://orcid.org/0000-0001-7460-4307)
- Bo-Wen Yu (ORCID: https://orcid.org/0000-0003-4748-7330)
- Jie Zheng (ORCID: https://orcid.org/0000-0002-2559-1412)
- Jing Zhang (ORCID: https://orcid.org/0000-0002-0734-3263)
- Zhe Li (ORCID: https://orcid.org/0000-0002-1052-9827)
Institutions
- Chinese Academy of Sciences (CN)
- Songshan Lake Materials Laboratory (CN)
- FZU ‒ Institute of Physics of the Academy of Sciences of the Czech Republic (CZ)
- Institute of Physics (CN)
- National Laboratory for Superconductivity (CN)
- University of Chinese Academy of Sciences (CN)
- Ningbo Institute of Industrial Technology (CN)
- Taiyuan University of Science and Technology (CN)
- Fuzhou University (CN)
Publication Details
- Journal
- Nature Communications
- Published
- 2024-11-15
- DOI
- https://doi.org/10.1038/s41467-024-54311-0
- Citations
- 3
- Primary Topic
- Magnetic and transport properties of perovskites and related materials
- Type
- article
- Field-Weighted Citation Impact
- 0.35
Funders
- National Science Foundation
- Salt Science Research Foundation
- National Natural Science Foundation of China
- Chinese Academy of Sciences
- Basic and Applied Basic Research Foundation of Guangdong Province