At DTU will held a two day workshop on materials computation. Special guests are Anna N. Morozovska (Institute of Physisc, Kiev, Ukraine) and prof Long-Qing Chen (Penn State University, USA). Anna N. Morozovska will present two lectures:
Analytical Description of Size Effects and Strain Engineering of Low-Dimensional Ferroelectric Materials
The lecture is devoted to the analytical methods based on the Landau-Ginzburg-Devonshire approach and variational principle, which allow the analytical description of size effects and strain engineering of low-dimensional ferroelectric materials, such as thin films and small nanoparticles. It will start with the introduction of the experimental evidence of the size-induced and strain-induced transitions and related phenomena in the low-dimensional ferroelectric materials. Next, we introduce the fundamentals of the Landau-Ginzburg-Devonshire approach combined with the
classical electrostatics and elasticity theory, and variational principle for the description of sizeinduced and strain-induced effects in ferroelectric thin films and small nanoparticles. The focus will be on the comparison with experimental results and finite element modelling, as well as on the theoretical predictions of the size- and straincontrol of polar and piezoelectric properties of low dimensional ferroelectric materials.
Ferri-ionic Coupling in CuInP2S6 Nanoflakes: High and Low Polarization States and Controllable Negative Capacitance
We consider nanoflakes of van der Waals ferrielectric CuInP2S6 covered by an ionic surface charge and reveal the appearance of polar states with relatively high polarization ~ 5 μC/cm2 and
stored free charge ~ 10 μC/cm2, which can mimic “mid-gap” states related with a surface fieldinduced transfer of Cu and/or In ions in the van der Waals gap. The change in the ionic screening degree and mismatch strains induce a broad range of the transitions between paraelectric phase, antiferroelectric, ferrielectric, and ferroelectric-like states in CuInP2S6 nanoflakes. We predict that the CuInP2S6 nanoflakes reveal features of the controllable negative capacitance effect, which make them attractive for advanced electronic devices, such as nano-capacitors and gate oxide
nanomaterials with reduced heat dissipation.
