Article abstract


Nature Materials 8, 892 - 897 (2009)
Published online: 18 October 2009 | doi:10.1038/nmat2557

Subject Categories: Magnetic materials | Surface and thin films

Enhanced ordering temperatures in antiferromagnetic manganite superlattices

S. J. May1, P. J. Ryan2, J. L. Robertson3, J.-W. Kim4, T. S. Santos5, E. Karapetrova4, J. L. Zarestky6, X. Zhai7, S. G. E. te Velthuis1, J. N. Eckstein7, S. D. Bader1,5 & A. Bhattacharya1,5


The disorder inherent to doping by cation substitution in the complex oxides can have profound effects on collective-ordered states. Here, we demonstrate that cation-site ordering achieved through digital-synthesis techniques can dramatically enhance the antiferromagnetic ordering temperatures of manganite films. Cation-ordered (LaMnO3)m/(SrMnO3)2m superlattices show Néel temperatures (TN) that are the highest of any La1−xSrxMnO3 compound, ~70K greater than compositionally equivalent randomly doped La1/3Sr2/3MnO3. The antiferromagnetic order is A-type, consisting of in-plane double-exchange-mediated ferromagnetic sheets coupled antiferromagnetically along the out-of-plane direction. Through synchrotron X-ray scattering, we have discovered an in-plane structural modulation that reduces the charge itinerancy and hence the ordering temperature within the ferromagnetic sheets, thereby limiting TN. This modulation is mitigated and driven to long wavelengths by cation ordering, enabling the higher TN values of the superlattices. These results provide insight into how cation-site ordering can enhance cooperative behaviour in oxides through subtle structural phenomena.

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  1. Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
  2. MUCAT, Ames Laboratory, Ames, Iowa 50010, USA
  3. Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
  4. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
  5. Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA
  6. Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
  7. Department of Physics, University of Illinois—Urbana-Champaign, Urbana, Illinois 60801, USA

Correspondence to: A. Bhattacharya1,5 e-mail: anand@anl.gov



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