Ferroelectric Switching in Hybrid Molecular-Beam-Epitaxy-Grown BaTiO₃ Films

Molecular beam epitaxy (MBE) is a promising synthesis technique for both heterostructure growth and epitaxial integration of ferroelectric BaTiO3. However, direct measurement of the remnant polarization (Pr) has not been previously reported in MBE-grown BaTiO3 films. We report the in situ growth of an all-epitaxial SrRuO3/BaTiO3/SrRuO3 heterostructure on Nb-doped SrTiO3 (001) substrates by hybrid MBE using metal–organic precursors. This capacitor structure consisting of 16 nm SrRuO3/40 nm BaTiO3/16 nm SrRuO3 shows hysteretic polarization–electric field (P–E) curves with Pr ∼ 15 μC cm–2 at frequencies ranging from 500 Hz to 20 kHz, after isolating the intrinsic ferroelectric response from non-ferroelectric contributions using the Positive-Up-Negative-Down (PUND) method. We hypothesize that the asymmetry in switching behavior and current leakage has origins in structural defects. This work opens the door to defect-engineered ferroelectric BaTiO3-based heterostructures grown by hybrid MBE for future electronic, photonic and spintronic applications.