posted on 2020-03-10, 08:45authored byLena Wysocki, Jörg Schöpf, Michael Ziese, Lin Yang, András Kovács, Lei Jin, Rolf B. Versteeg, Andrea Bliesener, Felix Gunkel, Lior Kornblum, Regina Dittmann, Paul H. M. van Loosdrecht, Ionela Lindfors-Vrejoiu
SrRuO3, a 4d ferromagnet with multiple Weyl nodes at
the Fermi level, offers a rich playground to design epitaxial heterostructures
and superlattices with fascinating magnetic and magnetotransport properties.
Interfacing ultrathin SrRuO3 layers with large spin–orbit
coupling 5d transition-metal oxides, such as SrIrO3, results
in pronounced peaklike anomalies in the magnetic field dependence
of the Hall resistivity. Such anomalies have been attributed either
to the formation of Néel-type skyrmions or to modifications
of the Berry curvature of the topologically nontrivial conduction
bands near the Fermi level of SrRuO3. Here, epitaxial multilayers
based on SrRuO3 interfaced with 5d perovskite oxides, such
as SrIrO3 and SrHfO3, were studied. This work
focuses on the magnetotransport properties of the multilayers, aiming
to unravel the role played by the interfaces with 5d perovskites in
the peaklike anomalies of the Hall resistance loops of SrRuO3 layers. Interfacing with large band gap insulating SrHfO3 layers did not influence the anomalous Hall resistance loops, while
interfacing with the nominally paramagnetic semimetal SrIrO3 resulted in pronounced peaklike anomalies, which have been lately
attributed to a topological Hall effect contribution as a result of
skyrmions. This interpretation is, however, under strong debate and
lately alternative causes, such as inhomogeneity of the thickness
and the electronic properties of the SrRuO3 layers, have
been considered. Aligned with these latter proposals, our findings
reveal the central role played in the anomalies of the Hall resistivity
loops by electronic inhomogeneity of SrRuO3 layers due
to the interfacing with semimetallic 5d5 SrIrO3.