  The topological Hall effect (THE) has been discovered in ultrathin SrRuO3
(SRO) films, where the interface between the SRO layer and another oxide layer
breaks the inversion symmetry resulting in the appearance of THE. Thus, THE
only occurs in ultra-thin SRO films of several unit cells. In addition to
employing a heterostructure, the inversion symmetry can be broken intrinsically
in bulk SRO by introducing defects. In this study THE is observed in 60 nm
thick SRO films, in which defects and lattice distortions are introduced by
helium ion irradiation. The irradiated SRO films exhibit a pronounced THE in a
wide temperature range from 5 K to 80 K. These observations can be attributed
to the emergence of Dzyaloshinskii-Moriya interaction as a result of artificial
inversion symmetry breaking associated to the lattice defect engineering. The
creation and control of the THE in oxide single layers can be realized by ex
situ film processing. Therefore, this work provides new insights into the THE
and illustrates a promising strategy to design novel spintronics devices.
