Ferromagnetic tendencies at the surface of AF/CO bulk manganites

ORAL

Abstract

Previous investigations have shown that the surface of a ferromagnetic (FM) manganite has antiferromagnetic (AFM) tendencies. However, the development of ferromagnetism has been observed experimentally in some AFM charge-ordered (CO) manganites by reducing the grain size down to the nanoscale. Similar phenomenon was also found in other nanosized CO oxides, such as La$_{1/3}$Sr$_{2/3}$FeO$_{3}$. To clarify these puzzling observations, using Monte Carlo techniques we studied the FM Kondo model, using open boundary conditions to simulate a surface. For some values of the couplings, the previously known tendency to an AFM outer shell was found for the case of a bulk FM state. But for other couplings, the opposite effect was observed: the existence of a FM layer at the surface of a AFM/CO material. Details will be provided in this presentation.

*Work supported by NSF DMR-0706020 and by the Division of Materials Science and Engineering, US DOE, under contract with UT-Battelle, LLC

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Authors

  • Shuai Dong

    • Department of Physics and Astronomy, University of Tennessee and Materials Science and Technology Division, Oak Ridge National Laboratory

  • Rong Yu

    • Department of Physics and Astronomy, University of Tennessee and Materials Science and Technology Division, Oak Ridge National Laboratory
    • Department of Physics, University of Tennessee

  • Seiji Yunoki

    • Department of Physics and Astronomy, University of Tennessee and Materials Science and Technology Division, Oak Ridge National Laboratory

  • Elbio Dagotto

    • Oak Ridge Natl. Lab. and Univ. Tennessee, TN, USA
    • Department of Physics and Astronomy, University of Tennessee and Materials Science and Technology Division, Oak Ridge National Laboratory
    • Department of Physics, University of Tennessee and Condensed Matter Sciences Division, ORNL