Nanotechnology 22, 254025 (2011)

M. Ziese, E. Pippel, E. Nikulina, M. Arredondo and I. Vrejoiu

Abstract

La_0.7Sr_0.3MnO₃–SrRuO₃ superlattices with and without nanometrically thin SrTiO₃, BaTiO₃ and Ba_0.7Sr_0.3TiO₃ interlayers were grown by pulsed laser deposition. Transmission electron microscopy studies showed coherent growth of La_0.7Sr_0.3MnO₃, SrRuO₃ and SrTiO₃ layers with atomically sharp interfaces, even if individual layers were as thin as one or two unit cells. In contrast, misfit dislocations and unit cell high interfacial steps were observed at the interfaces between BaTiO₃ and one of the ferromagnetic layers. The presence of the interlayers as well as these extended defects had a significant influence on the magnetic properties of the superlattices, especially on the antiferromagnetic interlayer exchange coupling between the La_0.7Sr_0.3MnO₃ and SrRuO₃ layers and the exchange biasing. Surprisingly, exchange biasing was found to increase with decreasing strength of the antiferromagnetic interlayer exchange coupling. This was explained by different magnetization reversal mechanisms acting in the regimes of strong and weak interlayer exchange coupling.