Magnetoresistance at artificial interfaces in epitaxial ferromagnetic thin films

Epitaxial La2/3Sr1/3MnO3 and SrRuO3 thin films have been grown by laser ablation on single-crystalline SrTiO3 substrates. Prior to manganite or ruthenate deposition tracks have been patterned on the SrTiO3 substrate by using an appropriately focused laser beam. In the experiments here reported linear tracks have been formed. The magnetotransport properties of the films, particularly the magnetoresistance, along paths parallel and perpendicular to the track have been extensively investigated and compared to similar data recorded on films grown on bicrystalline STO substrates. Whereas in LSMO a significant low-field tunnel magnetoresistance develops across the artificial interface, in SRO this tunnel contribution is absent. However, a significant high-field magnetoresistance is observed for both metallic and ferromagnetic systems. The results are analysed and discussed within the framework of the current understanding of double exchange and itinerant ferromagnets. Magnetoresistance data for various configurations of the track array are presented. (C) 2000 Elsevier Science B.V. All rights reserved.