Stark anisotrope magnetische Eigenschaften von ultradünnen (La,Na) MnO 3 ‐Filmen auf LaAlO 3 (001)‐Substraten

Magnetic measurements and resonance measurements have been carried out on ultrathin (20 nm) films of sodium‐doped lanthanum manganite fabricated by magnetron sputtering on single crystalline LaAlO 3 (001) substrates. Complex behavior of magnetization and magnetic anisotropy has been revealed. It is shown that an out‐of‐plane alignment of the film magnetization is characteristic of the films at low temperatures. As temperature increases, a spin‐reorientation transition occurs at about 160 K and in‐plane alignment of magnetization becomes more preferable. Further increase in temperature results in an isotropic behavior of magnetization as temperature approaches and crosses the Curie point (≈270 K). It is concluded that anisotropy energy, originated from a substrate‐induced compressive strain, is responsible for the unusual behavior of the ultrathin films of sodium‐doped manganites.