Abstract
Emergent phenomena at heterointerfaces are directly associated with the bonding geometry of adjacent layers. Effective control of accessible parameters, such as the bond length and bonding angles, offers an elegant method to tailor competing energies of the electronic and magnetic ground states. In this study, we construct unit-thick syntactic layers of cobaltites within a strongly tilted octahedral matrix via atomically precise synthesis. The octahedral tilt patterns of adjacent layers propagate into cobaltites, leading to a continuation of octahedral tilting while maintaining substantial misfit tensile strain. These effects induce severe rumpling within an atomic plane of neighboring layers, further triggering the electronic reconstruction between the splitting orbitals. First-principles calculations reveal that the cobalt ions transit to a higher spin state level upon octahedral tilting, resulting in robust ferromagnetism in ultrathin cobaltites. This work demonstrates a design methodology for fine-tuning the lattice and spin degrees of freedom in correlated quantum heterostructures by exploiting epitaxial geometric engineering.
Original language | English |
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Article number | eabq3981 |
Journal | Science Advances |
Volume | 8 |
Issue number | 43 |
DOIs | |
State | Published - Oct 2022 |
Funding
This work was supported by the National Key Basic Research Program of China (grant nos. 2020YFA0309100 and 2019YFA0308500), the National Natural Science Foundation of China (grant nos. 11974390, 11721404, 11874412, 12174364, and 12174437), the Beijing Nova Program of Science and Technology (grant no. Z191100001119112), the Beijing Natural Science Foundation (grant no. 2202060), the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology, and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (grant no. XDB33030200). Q.L. acknowledges support by Users with Excellence Program of Hefei Science Center CAS (no. 2021HSC-UE003) and the Fundamental Research Funds for the Central Universities (no. wk2310000104). The XAS and XLD experiments were conducted at the beamline 4B9B of the BSRF of the Institute of High Energy Physics, Chinese Academy of Sciences. The XMCD experiments were performed at National Synchrotron Radiation Laboratory (NSRL) in China via user proposals. The PNR experiments were conducted using the magnetism reflectometer (MR, BL-4A) at the Spallation Neutron Source (SNS), a DOE Office of Science User Facility operated by ORNL.
Funders | Funder number |
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Beijing Nova Program of Science and Technology | Z191100001119112 |
Office of Science | |
Oak Ridge National Laboratory | |
National Natural Science Foundation of China | 12174437, 11874412, 11974390, 12174364, 11721404 |
Chinese Academy of Sciences | XDB33030200 |
Natural Science Foundation of Beijing Municipality | 2202060 |
Institute of High Energy Physics | |
National Key Research and Development Program of China | 2019YFA0308500, 2020YFA0309100 |
Fundamental Research Funds for the Central Universities | wk2310000104 |
Hefei Science Center, Chinese Academy of Sciences | 2021HSC-UE003 |