M-type barium hexaferrite synthesis and characterization for phase shifter applications

A. T. Wise
J. Rocks
D. E. Laughlin
M. E. McHenry
S. D. Yoon
C. Vittoria, Northeastern University
V. G. Harris, Northeastern University

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he following article appeared in Journal of Applied Physics 109, 07E535 (2011). DOI:10.1063/1.3559471 (http://dx.doi.org/10.1063/1.3559471).

Abstract

M-type barium hexaferrite films have been grown by liquid phase epitaxy and examined by x-ray diffraction, scanning electron microscopy, atomic force microscopy, and conventional and Lorentz-mode transmission electron microscopy (TEM). These films exhibit a diamond chevron shaped "brick wall" microstructure with c-axis oriented hexaferrite platelets. The films are oriented with their c axes in-plane, and parallel to the M-plane sapphire substrate, and exhibit a 30 degrees rotation about the c axis with respect to the substrate. Rocking curves showed (20-20) and (22-40) FWHM values of 1.09 degrees and 1.56 degrees, respectively, for the thinner of two samples, and 0.31 degrees and 0.50 degrees for the thicker sample. The magnetic domain structures have been characterized by Lorentz-mode TEM and the domain walls were found to be pinned to small angle tilt boundaries. Using the measured rocking curve values, the effect of the overall crystalline misorientation on the dispersion of the magnetocrystalline anisotropy of the samples is estimated to be less than half a percent.