arXiv subjects

Denis Alikin

Publications and source records attributed to Denis Alikin.

3 recordsLinked to original sources

arXiv2026

When Screening Current Controls Ferroelectric Switching: From Field-Limited to Current-Limited Regimes

Tip-induced switching in ferroelectrics is commonly framed as a field-driven process controlled by domain-wall kinetics. Here we argue for a more universal viewpoint: under a scanning probe, polarization reversal is fundamentally constrained by how fast screening charge can be supplied and redistributed. By combining local switching experiments with finite-element simulations, we identify a screening-current-limited mechanism in which charge injection and its space-charge-limited relaxation set the pace of switching and the scaling of domain growth. This framework naturally explains regime changes and the apparent breakdown of intrinsic domain-wall laws often inferred in the nanoscale piezoelectric hysteresis measurements. Beyond a reinterpretation of tip switching, the results position screening currents as a hidden control parameter of ferroelectric reversal across materials, turning current regulation into a practical handle for deterministic nanoscale domain engineering.

cond-mat.mes-hall↗

arXiv2026

Instability-driven mechanically locked states in functional oxide membranes

Mechanical instabilities in thin solids offer a powerful route to engineer nonlinear responses, yet their controlled use in functional crystalline oxides has remained largely unexplored. Notably, by changing the aspect ratio of solids, the energy landscape around equilibrium can be modified to induce non-linearities under lateral stresses through non-lateral deformations. These nonlinear systems can develop multiple local energy minima where the system can settle and switch between states through the application of a driving force. Crucially, recent advances in oxide thin film growth have enabled the fabrication of freestanding oxide membranes, paving a viable path for their use in bistable architecture, particularly at the nanoscale. Here, we demonstrate that freestanding oxide membranes, such as SrTiO3 (STO) and BaTiO3 (BTO), relax into well-defined metastable buckling states when transferred onto lithographically defined cavities. The membrane deformation is determined by the interplay between built-in residual strain, bending stiffness, and cavity geometry, resulting in reproducible bistable states with distinct strain distributions. Using a combination of atomic force microscopy, in-contact Kelvin probe measurements, and finite-element modelling, we reveal that these mechanically locked states directly shape the electromechanical potential landscape of ferroelectric BaTiO3. We further demonstrate reversible snapthrough transitions between mechanically degenerate states, establishing complex oxides as deterministic, geometry-tunable building blocks for nonlinear nanoelectromechanical architectures. Our results illustrate a general strategy for exploiting mechanical instabilities to encode and manipulate functional responses in ultrathin crystalline membranes.

cond-mat.mtrl-sci↗

arXiv2019

Polarization-dependent conductivity of grain boundaries in BiFeO3 thin films

Charge transport across the interfaces in complex oxides attracts a lot of attention because it allows creating novel functionalities useful for device applications. In particular, it has been observed that movable domain walls in epitaxial BiFeO3 films possess enhanced conductivity that can be used for read out in ferroelectric-based memories. In this work, the relation between the polarization and conductivity in sol-gel BiFeO3 films with special emphasis on grain boundaries as natural interfaces in polycrystalline ferroelectrics is investigated. The grains exhibit self-organized domain structure in these films, so that the "domain clusters" consisting of several grains with aligned polarization directions are formed. Surprisingly, grain boundaries between these clusters (with antiparallel polarization direction) have significantly higher electrical conductivity in comparison to "inter-cluster" grain boundaries, in which the conductivity was even smaller than in the bulk. As such, polarization-dependent conductivity of the grain boundaries was observed for the first time in ferroelectric thin films. The results are rationalized by thermodynamic modelling combined with finite element simulations of the charge and stress accumulation at the grain boundaries giving major contribution to conductivity. The observed polarization-dependent conductivity of grain boundaries in ferroelectrics opens up a new avenue for exploiting these materials in electronic devices.

cond-mat.mtrl-sci↗