Interfacial control of chiral magnetic interactions and Hall effect in Iridate-manganite superlattices*

One of the most intriguing outcomes of symmetry breaking and spin-obit interactions in magnetic systems is the possibility to create non-collinear and chiral spin textures. The Dzyaloshinskii-Moriya interaction (DMI) results from strong spin-orbit coupling and broken inversion symmetry to generate magnetization rotations with fixed chirality. The discovery of magnetic skyrmions originating from strong DMI in metal thin films has led to an explosion of efforts to manipulate magnetic phases originating from interfaces. I will describe our progress to understand interface-induced magnetism in epitaxial 3d/5d iridate/manganite superlattices. Our previous work on high-quality epitaxially stabilized SrMnO₃/SrIrO₃ superlattices revealed charge-transfer induced interfacial collinear ferromagnetism and an anomalous Hall effect [1,2]. In LaMnO₃/SrIrO₃ superlattices, we find a large additional topological Hall effect arising from the interaction of charge carriers with a noncoplanar chiral spin texture induced by interfacial DMI [3]. I will describe how the interfacial atomic layer stacking and symmetry enabled by the nonmagnetic A-sites determine the competition between collinear and chiral magnetic interactions originating from the oxide interface. These results will be compared with magnetometry measurements, soft and hard x-ray experiments, which provide a comparison of the bulk and interface electronic and magnetic properties. Our findings provide insight to the manipulation of chiral magnetism from atomic-scale control of DMI at oxide interfaces.

[1] J. Nichols et al., Nat. Commun. 7, 12721 (2016).
[2] S. Okamoto et al., Nano Lett. 17, 2126 (2017).
[3] P. Bruno et al., Phys. Rev. Lett. 93, 096806 (2004).