Proton-controlled Dzyaloshinskii-Moriya interaction and topological Hall effect in hydrogenated strontium ruthenate.

Abstract

The Topological Hall effect (THE) is a fascinating physical phenomenon related to topological spin textures, serving as a powerful electrical probe for detecting and understanding these unconventional magnetic orders and skyrmions. Recently, the THE has been observed in strontium ruthenate (SrRuO₃, SRO) thin films and its heterostructures, which originates from the disruption of interfacial inversion symmetry and Dzyaloshinskii-Moriya interaction (DMI). Here, we demonstrate a practically pure proton doping effect for controlling the DMI and THE in the SRO epitaxial films using the Pt electrode-assisted hydrogenation method. The hydrogenation process can realize approximately 0.8 protons per unit cell incorporating into the SRO films (thickness >10 nm) without causing significant lattice expansion and oxygen vacancies. Consistent with first-principles calculations, atomic-scale observations confirm that the proton doping induces a vertical displacement of Ru and O atoms in hydrogenated SRO (H-SRO), which remarkably enhances the DMI and leads to the emergence of the THE. More importantly, the proton doping drives two distinct topological signals in the ferromagnetic H-SRO, exhibiting greater THE values but no occurrence of structural transition. Our study has demonstrated that catalysis-assisted hydrogenation is an efficient strategy for manipulating the emerging THE and magnetic textures in correlated oxide thin films.