Theoretical investigations of Topological Hall Effect at Manganite/Iridate Oxide Interfaces

We study topological Hall effect at the interface between La1−xSrxMnO3 and SrIrO3. We show that the ferromagnetism at the manganite layer, in conjunction with the Dzyaloshinskii-Moriya (DM) interaction which arises at the interface due to broken inversion symmetry and strong spin-orbit coupling from the iridate layer produces a skyrmion crystal (SkX) phase in the presence of an external magnetic field. Using the Monte Carlo technique and a two-orbital spin-fermion model for manganites, we obtain phase diagrams which reveal, at low temperatures, a clear SkX phase and also a low-field spin-spiral phase. Increasing temperature, a skyrmion-gas phase, precursor of the SkX phase upon cooling, was identified. The topological Hall effect primarily appears in the SkX phase. We also show that a planar topological Hall effect can robustly appear at oxide interfaces from conical spin spirals at oxide interfaces, without skyrmions, when the magnetic field is applied parallel to the interface plane.

[1] N. Mohanta, E. Dagotto and S. Okamoto, Phys. Rev. B 100, 064429 (2019)
[2] N. Mohanta, S. Okamoto and E. Dagotto, in preparation.