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 significant misfit tensile strain. These effects induce severe rumpling within an atomic plane of neighboring layers triggers the electronic reconstruction between the splitting orbitals. First-principles calculations reveal that the cobalt ions transits 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.
@article{arxiv.2207.03298,
title = {Atomically engineered cobaltite layers for robust ferromagnetism},
author = {Shengru Chen and Qinghua Zhang and Xujing Li and Jiali Zhao and Shan Lin and Qiao Jin and Haitao Hong and Amanda Huon and Timothy Charlton and Qian Li and Wensheng Yan and Jiaou Wang and Chen Ge and Can Wang and Baotian Wang and Michael R. Fitzsimmons and Haizhong Guo and Lin Gu and Wen Yin and Kuijuan Jin and Er Jia Guo},
journal= {arXiv preprint arXiv:2207.03298},
year = {2022}
}