Phys. Status Solidi B (2019) 1900628

M. Ziese, F. Bern, P.D. Esquinazi, and I. Lindfors-Vrejoiu

Abstract
Noncollinear spin textures such as skyrmions lead to a novel Hall effect contribution called the topological Hall effect. In recent years, research has focused on the Weyl metal SrRuO₃ with topological signatures reported for SrRuO₃ layers adjacent to layers with strong spin–orbit coupling. However, SrRuO₃ films are known to be prone to structural modifications when interfaced with different materials. In this work the Hall effect of SrRuO₃/La_0.7Sr_0.3MnO₃ superlattices (SLs) is correlated with structural and magnetic information to study whether a topological Hall effect is induced by interfacing to ferromagnetic layers. High‐quality SLs with ultrathin layers are fabricated by pulsed laser deposition on SrTiO₃ substrates. The symmetry of the SrRuO₃ layers is studied by angular magnetoresistance measurements and the magnetocrystalline anisotropy by magnetization measurements. Two SLs are compared in detail, both with 8 unit cell thick SrRuO₃ layers, but with La_0.7Sr_0.3MnO₃ layers 2 and 4 unit cell thick. Only the sample with 2 unit cell thick manganite layers shows features resembling a topological Hall effect. Depending on the La_0.7Sr_0.3MnO₃ layer thickness the SrRuO₃ crystalline symmetry is orthorhombic or tetragonal. The results indicate that the topological Hall effect features arise from an intricate interplay between magnetocrystalline anisotropy and antiferromagnetic interlayer coupling.

DOI