Fig. 4: Robust ferroelectricity in HfO2/ZrO2 superlattices and its microscopic origin.
a XRD patterns of the n = 3 superlattices with different total film thickness (4−100 nm). b P–E hysteresis loop, corresponding I–E curve and dielectric constant-electric field curve (inset) of 4 nm superlattice, which highlights the ferroelectricity of the superlattices at ultra-thin scales. c Endurance performances of 6 nm HZO and superlattice. d P–E hysteresis loops and corresponding I–E curves (inset) of 10 nm, 20 nm, 40 nm, 60 nm and 100 nm superlattices. e Remnant polarization of superlattices and HZO films at different thickness. f Comparison of minimum coercive fields of our superlattices with representative reported epitaxial HfO2-based ferroelectric materials. g Phase transition kinetic energy barrier of zirconia. h Schematic of the atomic interface model (left). The interfacial forming energy of different systems and the critical thickness of the polar phase (right).
