The proposal that very small Néel skyrmions can form in ${\mathrm{SrRuO}}_3/{\mathrm{SrIrO}}_3$ epitaxial bilayers and that the electric field effect can be used to manipulate these skyrmions in gated devices strongly stimulated the recent research of ${\mathrm{SrRuO}}_3$ heterostructures. A strong interfacial Dzyaloshinskii-Moriya interaction was considered as the driving force for the formation of skyrmions in ${\mathrm{SrRuO}}_3/{\mathrm{SrIrO}}_3$ bilayers. Here, we investigated nominally symmetric heterostructures in which an ultrathin ferromagnetic ${\mathrm{SrRuO}}_3$ layer is sandwiched between large spin-orbit coupling ${\mathrm{SrIrO}}_3$ layers, for which the conditions are not favorable for the emergence of a net interfacial Dzyaloshinskii-Moriya interaction. Previously the formation of skyrmions in the asymmetric ${\mathrm{SrRuO}}_3/{\mathrm{SrIrO}}_3$ bilayers was inferred from anomalous Hall resistance loops showing humplike features that resembled topological Hall effect contributions. Symmetric ${\mathrm{SrIrO}}_3/{\mathrm{SrRuO}}_3/{\mathrm{SrIrO}}_3$ trilayers do not show hump anomalies in the Hall loops. However, the anomalous Hall resistance loops of symmetric multilayers, in which the trilayer is stacked several times, do exhibit the humplike structures, similar to the asymmetric ${\mathrm{SrRuO}}_3/{\mathrm{SrIrO}}_3$ bilayers. The origin of the Hall effect loop anomalies likely resides in unavoidable differences in the electronic and magnetic properties of the individual ${\mathrm{SrRuO}}_3$ layers rather than in the formation of skyrmions.

Magnetic interlayer coupling is a key ingredient in designing magnetic multilayers with functionalities that reach out to the realm of applications. In epitaxial ferromagnetic (FM) oxide multilayers, the magnetic interlayer coupling is, however, less studied and its prediction is often a challenging task. Ultrathin FM ${\mathrm{SrRuO}}_3$ epitaxial films with perpendicular magnetic anisotropy, interfaced with suitable oxides, may be susceptible of forming skyrmions. Hence, a strong FM interlayer coupling would be beneficial to achieve uniform switching behavior of a ${\mathrm{SrRuO}}_3$-based multilayer. Previous studies reported that the coupling of two ${\mathrm{SrRuO}}_3$ layers separated by a non-FM oxide spacer is at best weakly FM and the two FM layers switch at markedly different fields. Here we study the magnetic interlayer coupling between two FM ${\mathrm{SrRuO}}_3$ layers separated by ultrathin ${\mathrm{LaNiO}}_3$ in epitaxial heterostructures grown on ${\mathrm{SrTiO}}_3$(100) single crystals. We found that FM ${\mathrm{SrRuO}}_3$ layers separated by 2 monolayers (MLs) thick ${\mathrm{LaNiO}}_3$ show weak FM interlayer coupling of about $106\mu \mathrm{J}/m^2$ at 10 K. The coupling becomes strongly FM for four MLs thick (about 1.6 nm) ${\mathrm{LaNiO}}_3$ spacers and the two ${\mathrm{SrRuO}}_3$ layers reverse their magnetization at a common value of the perpendicular magnetic field. This is likely due to a transition of the ${\mathrm{LaNiO}}_3$ spacer from insulating to metallic, as its thickness increases.

A key element to tailor the properties of magnetic multilayers is the coupling between the individual magnetic layers. In the case of skyrmion hosting multilayers, coupling of skyrmions across the magnetic layers is highly desirable. Here, the magnetic interlayer coupling was studied in epitaxial all-oxide heterostructures of ferromagnetic perovskite SrRuO${}_3$ layers separated by spacers of the strong spin–orbit coupling oxide SrIrO${}_3$ . This combination of oxide layers is being discussed as a potential candidate system to host Néel skyrmions. First order reversal curve (FORC) measurements were performed in order to distinguish between magnetic switching processes of the individual layers and to disentangle the signal of soft magnetic impurities from the sample signal. Additionally, FORC investigations enabled us to determine whether the coupling between the magnetic layers is ferromagnetic or antiferromagnetic. The observed interlayer coupling strength was very weak for the heterostructure with a two monolayer (ML) thick SrIrO${}_3$ spacer, and no coupling was observed for spacers of 6 and 12 ML thickness. The decoupling of the magnetic SrRuO${}_3$ layers due to the SrIrO${}_3$ spacer is a disadvantage for the study of skyrmions in such multilayers and indicates that other oxides have to be identified for realizing strong magnetic coupling.

Controlling the magnetic anisotropy of materials is important in a variety of applications including magnetic memories, spintronic sensors, and skyrmion‐based devices. Ru‐substituted La_0.7Sr_0.3MnO₃ (Ru‐LSMO) is an emerging material, showing tilted magnetic anisotropy (TMA) and possible nontrivial magnetic topologies. Here anisotropic in‐plane magnetization is reported in moderately compressed Ru‐LSMO films, coexisting with TMA. This combination is attractive for technological applications, such as spin‐orbit torque (SOT) based devices and other spintronic applications. A microstructural analysis of films of this material is presented, and Ru single ion anisotropy and strain‐induced structural mechanisms are found to be responsible for both the in‐plane anisotropy and the TMA. The manifestation of these properties in a correlated oxide with Curie temperature near room temperature highlights an attractive platform for technological realization of SOT and other spintronic devices. Illustrating the mechanisms behind these properties provides the necessary engineering space for harnessing these phenomena for practical devices.

A novel Ni-Cr-Si-B filler metal (JNi-5) was designed and further fabricated into the amorphous brazing filler metal for joining the GH4169 alloy. The effect of brazing temperature on the microstructure and mechanical properties of GH4169 joints was investigated. The typical microstructure of the joint at 1030 °C is composed of four specific zones: the base metal (BM), heat-affected zone (HAZ), isothermal solidification zone (ISZ), and athermal solidification zone (ASZ). The typical microstructure of the joint is GH4169/(Nb, Mo)-rich boride+(Cr, Nb, Mo)-rich boride/γ(Ni)/Ni-rich boride+γ(Ni)/γ(Ni)/(Cr, Nb, Mo)-rich boride+(Nb, Mo)-rich boride/GH4169. As the temperature increased, the HAZ continued to widen and the ASZ depleted at 1090 °C and 1120 °C. Additionally, the borides within the HAZ coarsened at temperatures of 1090 °C and 1120 °C. At 1030 °C, the fracture path is in the ASZ, and the existence of the brittle phase in the ASZ provides the potential origin for crack growth. The fracture mode is a quasi-cleavage fracture. At 1060 °C, 1090 °C, and 1120 °C, the fracture behavior mainly happened in the HAZ, and the existence of borides in the HAZ provides the potential origin for crack growth. Namely, the shear strength of joints was principally dominated by the brittle precipitations in the HAZ. The fracture mode of these joints is the hybrid ductile. At 1060 °C, the shear strength of the obtained joint is the highest value (693.78 MPa) due to the volume fraction increase in the Ni-based solid solution. Finally, the optimized brazing parameter of 1060 °C/10 min was determined, and the corresponding highest shear strength of 693.78 MPa was obtained owing to the increased content of the Ni-based solid solution in the joint.