Nano Lett., 12 (8), pp 4276–4281 (2012)

M. Ziese, F. Bern, E. Pippel, D. Hesse, and I. Vrejoiu

Abstract

The study of spatially confined complex oxides is of wide interest, since correlated electrons at interfaces might form exotic phases. Here La_0.7Sr_0.3MnO₃/SrRuO₃ superlattices with coherently grown interfaces were studied by structural techniques, magnetization, and magnetotransport measurements. Magnetization measurements showed that ferromagnetic order in ultrathin La_0.7Sr_0.3MnO₃ layers is stabilized in the superlattices down to layer thicknesses of at least two unit cells. This stabilization is destroyed, if the ferromagnetic layers are separated by two unit cell thick SrTiO₃ layers. The resistivity of the superlattices showed metallic behavior and was dominated by the conducting SrRuO₃ layers, the off-diagonal resistivity showed an anomalous Hall effect from both SrRuO₃ and La_0.7Sr_0.3MnO₃ layers. This shows that the La_0.7Sr_0.3MnO₃ layers are not only ferromagnetic but also highly conducting; probably a conducting hole gas is induced at the interfaces that stabilizes the ferromagnetic order. This result opens up an alternative route for the fabrication of two-dimensional systems with long-range ferromagnetic order.