Delta Doping of Ferromagnetism in Antiferromagnetic Manganite Superlattices

Phys. Rev. Lett. 107, 167202 – Published 12 October 2011
T. S. Santos, B. J. Kirby, S. Kumar, S. J. May, J. A. Borchers, B. B. Maranville, J. Zarestky, S. G. E. te Velthuis, J. van den Brink, and A. Bhattacharya

Abstract

We demonstrate that delta doping can be used to create a dimensionally confined region of metallic ferromagnetism in an antiferromagnetic (AFM) manganite host, without introducing any explicit disorder due to dopants or frustration of spins. Theoretical consideration of these additional carriers shows that they cause a local enhancement of ferromagnetic double exchange with respect to AFM superexchange, resulting in local canting of the AFM spins. This leads to a highly modulated magnetization, as measured by polarized neutron reflectometry. The spatial modulation of the canting is related to the spreading of charge from the doped layer and establishes a fundamental length scale for charge transfer, transformation of orbital occupancy, and magnetic order in these manganites. Furthermore, we confirm the existence of the canted, AFM state as was predicted by de Gennes [Phys. Rev. 118, 141 (1960)] but had remained elusive.

DOI: http://dx.doi.org/10.1103/PhysRevLett.107.167202

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  • Received 10 July 2011
  • Published 12 October 2011

© 2011 American Physical Society

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Authors & Affiliations

T. S. Santos1, B. J. Kirby2, S. Kumar3, S. J. May4,5, J. A. Borchers2, B. B. Maranville2, J. Zarestky6, S. G. E. te Velthuis5, J. van den Brink3, and A. Bhattacharya1,5,*

  • 1Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, USA
  • 2NIST Center for Neutron Research, NIST, Gaithersburg, Maryland 20899, USA
  • 3Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany
  • 4Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
  • 5Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
  • 6Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA

  • *anand@anl.gov

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