Anisotropic transport properties of epitaxial La2/3Ca1/3MnO3 thin films with different growth orientations (invited)

Thin films of La0.62+/-0.05Ca0.33+/-0.02MnO3-delta were grown by laser ablation on (1 0 0) LaAlO3, (1 0 0) and (1 1 0) SrTiO3 substrates. Detailed structural characterization by X-ray diffraction, texture and RBS-channeling shows that the films grow epitaxially, with either the manganite c-axis perpendicular to or in the plane of the films, Using the same deposition conditions, films with both orientations on SrTiO3 have similar magnetic and transport properties, with very close T-c. We found that the electrical resistivity (rho) and the magnetoresistance (Delta rho/rho) show crystalline anisotropy. The ratio between rho with the current along the a-axis and along the c-axis varies little with temperature, from 0.77 above T-c to 0.80 at low temperatures. The anisotropic magnetoresistance (with the applied field in the plane of the film, parallel or transverse to the current) is small at low temperatures and peaks close to T-c, with Delta rho/rho\\ - Delta rho/rho perpendicular to approximate to - 1.5%. The contributions of domain rotation and magnetocrystalline anisotropy to the anisotropic magnetoresistance are also discussed, and related to the inhomogeneous magnetic state below T-c. (C) 2000 Elsevier Science B.V. All rights reserved.