Magnetic Properties of ABO $_{3}$ -Type Epitaxial Multilayer Films Prepared by Spin-Coating Method

Epitaxial layered films of CaMnO₃ (CMO) and CaRuO₃ (CRO) were fabricated on a SrTiO₃(001) substrate by spin-coat method using organometallic solutions (metal alkoxides). Results of X-ray diffraction analysis and transmission electron microscopy indicate that the CaMO₃ (M=Mn, Ru) films were deposited epitaxially so as to align the pseudocubic (001) plane of CaMO₃ perpendicular to the (001) plane of the SrTiO₃ substrate. Ferromagnetism and metal-insulator transition were observed for the films with small CMO-layer thickness. The ferromagnetism was enhanced when the number of the interface between CMO and CRO layer was increased. The occurrence of ferromagnetism was explained assuming a mixed valence state of Ru and Mn ions and the double exchange interaction between Mn³⁺ and Mn⁴⁺ ions.