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Strain-induced high-temperature perovskite ferromagnetic insulator

  • Author(s): Meng, D
  • Guo, H
  • Cui, Z
  • Ma, C
  • Zhao, J
  • Lu, J
  • Xu, H
  • Wang, Z
  • Hu, X
  • Fu, Z
  • Peng, R
  • Guo, J
  • Zhai, X
  • Brown, GJ
  • Knize, R
  • Lu, Y
  • et al.
Abstract

© 2018 National Academy of Sciences. All rights reserved. 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 LaCoO3single-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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