Journal Article

Strain-induced high-temperature perovskite ferromagnetic insulator

Guo, Hongli, Cui, Zhangzhang, Guo, Jinghua, Lu, Jiangbo, Peng, Ranran, Fu, Zhengping, Xu, Hui, Knize, Randy, Brown, Gail J., Ma, Chao, Zhao, Jin, Hu, Xiang, Lu, Yalin, Wang, Zhicheng, Zhai, Xiaofang, Meng, Dechao

2018

Overview

Ferromagnetic insulators are required for many new magnetic devices, such as dissipationless quantum-spintronic devices, magnetic tunneling junctions, etc. Ferromagnetic insulators with a high Curie temperature and a high-symmetry structure are critical integration with common single-crystalline oxide films or substrates. So far, the commonly used ferromagnetic insulators mostly possess low-symmetry structures associated with a poor growth quality and widespread properties. The few known high-symmetry materials either have extremely low Curie temperatures (≤16 K), or require chemical doping of an otherwise antiferromagnetic matrix. Here we present compelling evidence that the LaCoO₃ single-crystalline thin film under tensile strain is a rare undoped perovskite ferromagnetic insulator with a remarkably high T C of up to 90 K. Both experiments and first-principles calculations demonstrate tensile-strain–induced ferromagnetism which does not exist in bulk LaCoO₃. The ferromagnetism is strongest within a nearly stoichiometric structure, disappearing when the Co2+ defect concentration reaches about 10%. Significant impact of the research includes demonstration of a strain-induced high-temperature ferromagnetic insulator, successful elevation of the transition over the liquid-nitrogen temperature, and high potential for integration into large-area device fabrication processes.

• Publisher: National Academy of Sciences,National Academy of Sciences, Washington, DC (United States)
• Subject: Antiferromagnetism / Applied Physical Sciences / Carbon dioxide / Cobalt / Crystal structure / Crystallinity / Curie temperature / Fabrication / Ferromagnetic materials / First principles / High temperature / Insulators / Integration / Magnetic devices / Nitrogen / Organic chemistry / Oxide coatings / Perovskite / Perovskites / Physical Sciences / Single crystals / Substrates / Symmetry / Temperature effects / Temperature requirements / Thin films