The emergence of new physical properties at the interfaces between complex oxides has always been of both fundamental and practical importance. Here, we report the observation of a giant topological Hall resistivity of $\sim 2.8\mu \mathrm{\Omega }\mathrm{cm}$ at room temperature in an epitaxial thin-film heterostructure of permalloy (Py, ${\mathrm{Ni}}_{80}{\mathrm{Fe}}_{20}$) and the half-metallic ferromagnet ${\mathrm{La}}_{0.65}{\mathrm{Sr}}_{0.35}{\mathrm{MnO}}_3$ (LSMO). This large magnitude of the topological Hall effect in the Py/LSMO heterostructure, compared to single-layer Py and LSMO thin films, is attributed to the optimized combination of ferromagnetism in LSMO and the strong spin-orbit-coupling-driven Rashba interaction at the interface. The introduction of a ferroelectric ${\mathrm{BaTiO}}_3$ sandwich layer in the Py/LSMO heterostructure also leads to an enhanced topological Hall resistivity compared to the single-layer Py thin film. Interestingly, magnetic force microscopy measurements reveal skyrmionlike features, suggesting the origin of the topological Hall effect. Our theoretical model calculations for the skyrmion lattice further indicate that the Rashba interaction, driven by the broken inversion symmetry in the Py/LSMO films, can account for the observed changes in the topological Hall effect at the interface. Our work opens the door for the potential use of Py/LSMO thin films in spintronic applications.

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• Topological Hall effect
• Interfaces
• Magnetic force microscopy
• Magnetization measurements
• Magneto-optical Kerr effect
• Tight-binding model