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Strain-induced high-temperature perovskite ferromagnetic insulator.

  • Author(s): Meng, Dechao
  • Guo, Hongli
  • Cui, Zhangzhang
  • Ma, Chao
  • Zhao, Jin
  • Lu, Jiangbo
  • Xu, Hui
  • Wang, Zhicheng
  • Hu, Xiang
  • Fu, Zhengping
  • Peng, Ranran
  • Guo, Jinghua
  • Zhai, Xiaofang
  • Brown, Gail J
  • Knize, Randy
  • Lu, Yalin
  • et al.
Abstract

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 TC 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.

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