Magnetoresistance anisotropy of strontium ruthenate films grown coherently on a TiO$_2$-terminated SrTiO$_3$(001) substrate

The SrRuO$_3$ films with a thickness of 80 nm have been coherently grown on a TiO$_2$-terminated SrTiO$_3$(001) substrate. Biaxial mechanical stresses induce a considerable difference between the unit cell parameters of the SrRuO$_3$ layer in the substrate plane ($\sim$3.904 $\mathring{\mathrm{A}}$) and along the normal to the substrate surface ($\sim$3.952 $\mathring{\mathrm{A}}$). The electrical resistivity of the SrRuO$_3$ film decreases practically linearly with increasing magnetic field strength $H$ when the latter is parallel to the current $I_b$ and the projection of the easy magnetization axis in the substrate plane. At $T$ = 4.2 K, $\mu_0H$ = 14 T, and the magnetic field oriented along the hard magnetization axis, the negative anisotropic magnetoresistance of the grown layers reaches 16% and exerts a notice-able effect on the response of electrical resistivity of the SrRuO$_3$ film to the magnetic field.