  The fabrication technique of freestanding oxide flakes by epitaxial lift-off
has made significant contributions to the multifunctional oxide thin film
research. Several highly impactful work have recently demonstrated the
robustness of freestanding oxide flakes retaining their desirable properties
after detachment from the substrate by dissolving away the water-soluble
Sr3Al2O6 buffer layer. Firstly, in epitaxial SrRuO3/SrIrO3 systems showing
Hall-humps reminiescence of Topological Hall Effect, first-principle
calculations revealed that octahedral tilts can modify the sign of
Dzyaloshinskii-Moriya interaction and avoid cancellation in a symmetric
trilayer structure. Secondly, freestanding flakes of the trilayer is also able
to retain the Hall-humps across a wide temperature range. The behaviour of
humps' peak field does not vary with field direction rotation away from surface
normal, consistent to a micromagnetic simulation result of N\'eel-type magnetic
Skyrmions. The layer-resolved octahedral tilts in the freestanding
heterostructures also crucially controls the occurrence of Hall-humps,
consistent to the insight from the epitaxial ones. This work offers a new
perspective to understanding Hall-humps in perovskite oxides, as well as
demonstrates the fabrication of oxide heterostructure membranes with high
interfacial quality.
