Interfaces of ferroic oxides can show complex magnetic textures which have strong impact on spintronics devices. This has been demonstrated recently for interfaces with insulating antiferromagnets such as $\mathrm{BiFe}{\mathrm{O}}_3$. Here, noncollinear spin textures which can be switched in very low magnetic field are reported for conducting ferromagnetic bilayers of $\mathrm{L}{\mathrm{a}}_{0.7}\mathrm{S}{\mathrm{r}}_{0.3}\mathrm{Mn}{\mathrm{O}}_3\text{−}\mathrm{SrRu}{\mathrm{O}}_3$ (LSMO-SRO). The magnetic order and switching are fundamentally different for bilayers coherently grown in reversed stacking sequence. The SRO top layer forms a persistent exchange spring which is antiferromagnetically coupled to LSMO and drives switching in low fields of a few milliteslas. Density functional theory reveals the crucial impact of the interface termination on the strength of Mn-Ru exchange coupling across the interface. The observation of an exchange spring agrees with ultrastrong coupling for the $\mathrm{Mn}{\mathrm{O}}_2/\mathrm{SrO}$ termination. Our results demonstrate low-field switching of noncollinear spin textures at an interface between conducting oxides, opening a pathway for manipulating and utilizing electron transport phenomena in controlled spin textures at oxide interfaces.

• Received 24 June 2018
• Revised 4 November 2018

DOI:https://doi.org/10.1103/PhysRevB.99.024416