Fig. 2: Mechanical pressure switching in 27 nm PTO membranes.
From: Ultralow-pressure-driven polarization switching in ferroelectric membranes
a Schematic images of samples: PTO film epitaxially grown on LNO/STO substrate (Epi/LNO/STO), freestanding PTO membrane transferred on LNO/STO substrate (FS||LNO/STO), platinum-coated silicon substrate (FS||Pt/Si) and gold-coated silicon substrate (FS||Au/Si). b The mechanical switching of ferroelectric polarization. The vertical PFM phase images with the increase of tip pressure in FS||Au/Si sample. Scale bar, 400 nm. c Ratio of switching area as a function of tip pressure. The inset shows threshold tip pressure Pth for different samples, which is defined as the load required to switch 90% of polarization volume. The thickness of coating layer (Pt or Au) is 100 nm. d Pth as a function of gold thickness (dAu) in FS||Au/Si samples, dAu = 0, 10, 20, 60, 100, 150 nm. The inset shows vertical PFM phase images: the purple region is loaded by the AFM tip with various pressures. Scale bar, 1 μm.
