Spontaneous resistivity anisotropy and band structure ofLa0.7Ca0.3MnO3andFe3O4films

Abstract

The spontaneous resistivity anisotropy of ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ and ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ films was measured as a function of temperature for various current and magnetic field directions. The anisotropic magnetoresistance was analyzed within the two-current model substituted by a calculation within an atomic state model. The magnetoresistance of ${\mathrm{La}}_{0.7}{\mathrm{Ca}}_{0.3}{\mathrm{MnO}}_{3}$ indicates that only majority electrons conduct current, whereas at least two bands of majority and minority character, respectively, contribute to the magnetotransport properties of ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}$ films. This finding is consistent with the small spin-polarization values observed for magnetite.