Fig. 1: Sample fabrication and basic characterization.

a Reflection high-energy electron diffraction (RHEED) intensity oscillations during the growth of Sr₃Al₂O₆ (SAO)—red line—and SrTiO₃ (STO)—blue line. Inset: RHEED diffraction pattern and atomic force microscopic (AFM) image of the SAO surface. The scale bar is 200 nm. b AFM images of the STO and c SrRuO₃ (SRO) film surfaces grown on top of the SAO. The scale bars are 1 μm. d X-ray diffraction measurement of a 10 unit cell (u.c.) STO film transferred on a Si/SiO₂ substrate. The expected peak positions are marked by the vertical dashed lines. e Rocking curve around the (002) reflection. f Schematics of the transfer of a thin SRO film onto a pre-patterned Si/SiO₂ substrate. g Optical image of suspended 9 u.c. SRO drums with a diameter of 13 μm. The purple surface is the area covered by the SRO film, including the three suspended drums marked by the arrows. The scale bar is 10 μm. h Set-up for interferometric displacement detection (VNA vector network analyser, PD photodiode, LD laser diode, BE beam expander, PBS polarized beam splitter, CM cold mirror).