A La(2/3)Ca(1/3)MnO(3) Hall bar with its long dimension roughly along the hard axis [110] was fabricated on a single-crystal-like tensilely strained film on SrTiO(3)(001). The anisotropic magnetoresistance (AMR) and planar Hall effect (PHE) have been studied at various external magnetic fields and temperatures. A phenomenological model in the high field limit is developed, and the galvanomagnetic tensor based on a tetragonal symmetry 4/mmm (D(4h)), applicable to epitaxial films on a substrate, has been obtained by expanding the tensor to the sixth order. The derived in-plane transverse resistance R(xy) shows a sin2φ(M) angular dependence, while the longitudinal R(xx) is constituted by not only a two-fold cos2φ(M) term, but also a four-fold cos4φ(M) term due to the square symmetry of the lattice. The model is in good agreement with the experimental results in high fields, while deviations are observed near the {100} easy axis with the decreasing field. Close inspection of the fitting parameters reveals the evolution of these term weights with temperature and magnetic field, which is distinct from conventional ferromagnetic metals and cannot be explained by the phenomenological model. An alternative mechanism for AMR, stemming from the magnetization-induced local orbit deformation through spin-orbit interaction, as previously proposed by O'Donnell et al, may be prevalent in manganites and other systems of complicated crystal structure.

The structural and transport properties of LaTiO(3+β/2) epitaxial thin films, grown at different oxygen pressures ranging from 6.6 × 10(-4) to 5 Pa, have been investigated. X-ray diffraction peaks of the films shift to lower angles with increasing oxygen pressure, indicative of a variation of the corresponding lattice spacing. All the films show T(2) dependence of resistivity over a large temperature range of ∼200 K, suggesting a band-filling-induced metallic Fermi-liquid behaviour. Upturns in resistivity have been revealed at low temperatures, which could be ascribed to the Anderson-localization effect caused by the cation vacancies. Furthermore, for the thin films grown at high oxygen pressures of 0.5 and 5 Pa, the dependence of resistivity on temperature shows a maximum at high temperatures. The maximum seems to support the argument that transition between t-orbital ordering and disordering plays an important role in dominating transport properties at high temperatures. Carrier density deduced from Hall coefficient increases with the decrease of oxygen content, and shows strong temperature dependence. From the experimental data, it can be asserted that in the LaTiO(3+β/2) thin films, besides the band filling effect, localization or disorder caused by La and Ti vacancy effects controls the unique transport properties.