Fe 3O 4/SrTiO 3/La 0.7Sr 0.3MnO 3 heterostructure: growth and properties.

Abstract

Fe 3O 4/SrTiO 3/La 0.7Sr 0.3MnO 3 (LSMO) epitaxial heterostructures were grown by pulsed laser deposition on LaAlO 3(001) substrates. The high structural quality of the heterostructures was established by X-ray diffraction measurements. The vertical (current perpendicular to plane-CPP) transport in the heterostructure, without and with the magnetic field applied in and perpendicular to the film plane was studied as a function of temperature. The magnetization behavior was also examined. Application of the magnetic field in the film plane is found to yield a large positive magnetoresistance (MR) while a perpendicular field is found to lead to a negative MR at low fields followed by a large positive MR at higher fields. The observed MR features do not show any obvious correlation with the hysterisis behavior of the ferromagnetic bilayers. A possible explanation of these results is given in terms of the relative differences in the majority and minority spin bands of the two ferromagnetic layers and the field induced modifications of domain structures therein.