Strain-induced spin states in atomically ordered cobaltites

Nano Lett. 2012 Sep 12;12(9):4966-70. doi: 10.1021/nl302562f. Epub 2012 Aug 16.


Epitaxial strain imposed in complex oxide thin films by heteroepitaxy is recognized as a powerful tool for identifying new properties and exploring the vast potential of materials performance. A particular example is LaCoO(3), a zero spin, nonmagnetic material in the bulk, whose strong ferromagnetism in a thin film remains enigmatic despite a decade of intense research. Here, we use scanning transmission electron microscopy complemented by X-ray and optical spectroscopy to study LaCoO(3) epitaxial thin films under different strain states. We observed an unconventional strain relaxation behavior resulting in stripe-like, lattice modulated patterns, which did not involve uncontrolled misfit dislocations or other defects. The modulation entails the formation of ferromagnetically ordered sheets comprising intermediate or high spin Co(3+), thus offering an unambiguous description for the exotic magnetism found in epitaxially strained LaCoO(3) films. This observation provides a novel route to tailoring the electronic and magnetic properties of functional oxide heterostructures.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cobalt / chemistry*
  • Elastic Modulus
  • Lanthanum / chemistry*
  • Magnetic Fields
  • Materials Testing
  • Metal Nanoparticles / chemistry*
  • Metal Nanoparticles / ultrastructure*
  • Oxides / chemistry*
  • Particle Size


  • Oxides
  • Cobalt
  • Lanthanum
  • cobalt oxide