Carrier Density Control of Magnetism and Hall Effects in EuTiO3 Films

The topological Hall effect is a hallmark of topologically nontrivial (chiral) spin textures and can be observed as a distinct, additional contribution in Hall measurements that is superposed on the ordinary and anomalous Hall effects. Oxide films and interfaces that support topologically nontrivial spin textures are interesting, because the potential for control by electric field effect and because proximity effects can be utilized to realize other exotic states within all-epitaxial heterostructures. In this talk, we discuss the role of carrier density and band structure in the topological and anomalous Hall effects in thin films of Eu_1-xSm_xTiO₃ grown by molecular beam epitaxy. The carrier density controls the sign and strength of the topological and anomalous Hall effects, the spin textures, and other effects, such as metamagnetic transitions. We will discuss the results in terms of the interactions between electronic and spin structures in this material.