Phase‐Field Study of Nanocavity‐Assisted Mechanical Switching in PbTiO₃ Thin Films

Abstract

Ferroelectric thin films hold significant promise in various nanoelectronic applications, demanding precise control over their domain structures. While electrical field‐driven polarization switching is currently employed, it often leads to undesirable side effects. In contrast, mechanical switching offers a voltage‐free alternative but faces challenges in thicker films. Recent breakthroughs have demonstrated stable mechanical switching in films up to 200 nm thick, attributed to the presence of nanocavities. These nanoscale voids are believed to facilitate domain transitions, serving as essential pinning centers. In this study, mechanical domain switching in thick ferroelectric films is investigated using phase‐field modeling, with a specific focus on evaluating the influence of nanocavities on domain stability. The effects of cavity parameters (size, depth, and dielectric properties) on mechanical switching stability under various applied pressures are systematically examined. The findings reveal the intricate interplay between these factors and outline the conditions for stable mechanical switching. Furthermore, phase‐field simulations are employed to showcase the energetic mechanisms governing nanocavity‐assisted mechanical switching, while also highlighting the pivotal role of these defects as pinning centers. This investigation elucidates the nanocavity‐assisted mechanical control of polarization and the potential for optimizing thin film design through nanocavity engineering, thus enabling mechanical switching across substantial film thicknesses.

Ultrafast and accurate prediction of polycrystalline hafnium oxide phase-field ferroelectric hysteresis using graph neural networks

“…To generate the dataset, phase-field simulations were carried out according to the method described in previous studies. 26,84 The simulations were run on a discretized grid with a size of 64 × 64 × 10, with a grid spacing of Δ x = Δ y = Δ z = 1 nm. The microstructure evolution of the P ( r , t ) spontaneous polarization is given by the time-dependent Landau Ginzburg (TDGL) equation:where L 0 is a kinetic coefficient and ψ is the total free energy, which includes the different energetic contributions, 26 …”