Thin Solid Films, Vol.625, 42-48, 2017
Low-field magnetoresistance and switching behavior of polycrystalline La0.66Sr0.34MnO3/YSZ(001) films with columnar grain structure
The La0.66Sr0.34MnO3 (LSMO) films with thickness d = 180-330 nm were grown by radio frequency magnetron sputtering on cubic yttria-stabilized zirconia, YSZ(001), at 750 degrees C. Coexistence of columnar grains with the averaged diameter of about 50 nm and (001) and (011) planes of a pseudocubic lattice oriented parallel to the film surface has been certified by transmission electron microscopy and x-ray diffraction investigations. Pole figure x-ray diffraction measurements revealed cube-on-cube growth of the LSMO(001) grains on YSZ(001) with 45 in-plane rotation meanwhile two in-plane orientations with the epitaxial relationships: [001](Lsmo)//[010](ysz) and [001](LSMO)//[100](ysz) have been certified for the LSMO(011) grains. Presence of high-angle grain boundaries between the columnar grains resulted enhanced electrical resistivity and low-field magnetoresistance associated to spin-polarized tunnelling of carriers. Electrical resistance versus magnetic field plots demonstrated the characteristic hysteresis behavior in the low field region (H < 80 kA/m) with peak-like maxima at H = +/- Hp. An unusual sharp resistance drop at H a Hp indicated for the films at T< 210 K and the observed variation of Hp with the angle between applied field and the film plane (a) defined by the Kondorsky relationship: Hp = H-p0/cos alpha demonstrate strong pinning of domain walls at grain boundaries. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:LSMO thin films on YSZ;Columnar grain structure;lntergrain resistance;LFMR;Switching behavior