Giant Enhancement of Magnetic Anisotropy in Ultrathin Manganite Films via Nanoscale 1D Periodic Depth Modulation

A. Rajapitamahuni, L. Zhang, M. A. Koten, V. R. Singh, J. D. Burton, E. Y. Tsymbal, J. E. Shield, and X. Hong
Phys. Rev. Lett. 116, 187201 – Published 2 May 2016
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Abstract

The relatively low magnetocrystalline anisotropy (MCA) in strongly correlated manganites (La,Sr)MnO3 has been a major hurdle for implementing them in spintronic applications. Here we report an unusual, giant enhancement of in-plane MCA in 6 nm La0.67Sr0.33MnO3 (LSMO) films grown on (001) SrTiO3 substrates when the top 2 nm is patterned into periodic stripes of 100 or 200 nm width. Planar Hall effect measurements reveal an emergent uniaxial anisotropy superimposed on one of the original biaxial easy axes for unpatterned LSMO along 110 directions, with a 50-fold enhanced anisotropy energy density of 5.6×106erg/cm3 within the nanostripes, comparable to the value for cobalt. The magnitude and direction of the uniaxial anisotropy exclude shape anisotropy and the step edge effect as its origin. High resolution transmission electron microscopy studies reveal a nonequilibrium strain distribution and drastic suppression in the c-axis lattice constant within the nanostructures, which is the driving mechanism for the enhanced uniaxial MCA, as suggested by first-principles density functional calculations.

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  • Received 22 July 2015

DOI:https://doi.org/10.1103/PhysRevLett.116.187201

© 2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. Rajapitamahuni1, L. Zhang1, M. A. Koten2, V. R. Singh1, J. D. Burton1, E. Y. Tsymbal1,3, J. E. Shield2,3, and X. Hong1,3,*

  • 1Department of Physics and Astronomy, University of Nebraska–Lincoln, Lincoln, Nebraska 68588-0299, USA
  • 2Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, Nebraska 68588-0299, USA
  • 3Nebraska Center for Materials and Nanoscience, University of Nebraska–Lincoln, Lincoln, Nebraska 68588-0299, USA

  • *Corresponding author. xhong2@unl.edu

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Vol. 116, Iss. 18 — 6 May 2016

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