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We investigated the structural and magnetic properties of bare SrRuO3 (SRO) ultrathin films and SrRuO3/SrIrO3/SrZrO3 (SRO/SIO/SZO: RIZ) trilayer heterostructures between 10 and 80 K, by comparing macroscopic data using the magneto-optical Kerr effect (MOKE) and magneto-transport (anomalous Hall effect: AHE), with nanoscale fingerprints when applying noncontact scanning force microscopy (nc-SFM) and magnetic force microscopy (MFM). SRO and RIZ ultrathin films were epitaxially grown at 650 °C onto vicinal SrTiO3 (100) single-crystalline substrates to a nominal thickness of 4 and 4/2/2 unit cells (uc), respectively. Our correlated analysis allows associating topographic sample features of overgrown individual layers to their residual magnetization, as is shown here to be relevant for interpreting the macroscopic AHE data. Although the hump-like features in the AHE suggest a magnetically textured skyrmion phase to exist around 55 K associated with the topological Hall effect (THE), both our MOKE and MFM data cannot support this theory for the ultrathin films investigated. In contrast, our SFM/MFM local-scale analysis finds the local coercive field to be strongly dependent on the effective layer thickness and stoichiometry in both the SRO and RIZ samples, with a huge impact on the local band structure. In fact, it is these variations that in turn mimic a potential THE through anomalies in the AHE resistivity loops. [ABSTRACT FROM AUTHOR]

Ferromagnetic La 0.7 Sr 0.3 Mn 1- x Ru x O 3 epitaxial multilayers with controlled variation of the Ru/Mn content were synthesized to engineer canted magnetic anisotropy and variable exchange interactions, and to explore the possibility of generating a Dzyaloshinskii-Moriya interaction. The ultimate aim of the multilayer design is to provide the conditions for the formation of domains with nontrivial magnetic topology in an oxide thin film system. Employing magnetic force microscopy and Lorentz transmission electron microscopy in varying perpendicular magnetic fields, magnetic stripe domains separated by Néel-type domain walls as well as Néel skyrmions smaller than 100 nm in diameter were observed. These findings are consistent with micromagnetic modeling, taking into account a sizable Dzyaloshinskii-Moriya interaction arising from the inversion symmetry breaking and possibly from strain effects in the multilayer system.