membranes*

We report a comprehensive ferroelectric domain study of free-standing PbZr_0.2Ti_0.8O₃ (PZT) and PZT/(La,Sr)MnO₃ (LSMO) membranes. We deposit 5 to 50 nm epitaxial PZT and PZT/LSMO thin films on Sr₃Al₂O₆ (SAO) buffered SrTiO₃ (STO) substrates using off-axis RF magnetron sputtering. The as-deposited thin films are single crystalline with no impurity phases, as confirmed by x-ray diffraction (XRD) measurements. Atomic force microscopy (AFM) studies show smooth surfaces with the RMS roughness of 0.5 nm for PZT and 0.8 nm for PZT/LSMO. We then immerse the samples in water to dissolve the SAO buffer layer and transfer the suspended oxide membranes to different conductive substrates, including Au and LSMO/STO. The RMS roughness of the membranes increases to 0.9 nm for PZT and 1.6 nm for PZT/LSMO, while XRD studies show they maintain the crystallinity. Piezo-response force microscopy (PFM) measurements reveal a uniform polarization down state for both samples, while the switching field of the PZT membranes is significantly higher than that of PZT/LSMO. We also discuss the effect of PZT thickness and the bottom electrode type on the domain wall roughness.