Anisotropic magnetoresistance in tetragonal La1-xCaxMnO delta thin films

We have fabricated thin films of La1-xCaxMnOdelta with tetragonal symmetry. For low temperatures and magnetic fields the measured magnetoresistance is anisotropic: initially positive for applied magnetic field perpendicular to the film plane and negative for field applied parallel to the film plane. At high temperatures the magnetoresistance is negative for all fields and field orientations. We also observe an in-plane magnetoresistance anisotropy with an angular dependence corresponding to that observed in transition metal ferromagnets. We suggest an interpretation requiring a substantial spin-orbit interaction in the material. (C) 1996 American Institute of Physics.