Control of polarization hysteresis temperature behavior by surface screening in thin ferroelectric films

Dr. Ganna Morozovska, (Ukraine)

Video was recorded during the 6th International research and practice Conference "Nanotechnolgy and Nanomaterials" (NANO-2018)

Theoretical analysis of free energy relief and temperature behaviour of hysteresis loops of polarization (P) and screening surface charge density (Σ) in the cases of electronic surface state and electron gas screenings, and also the screening by ions adsorbed on free surface of ferroelectric (FE) thin film is performed.

The dependence of the Σ on electric potential was considered as linear for the Bardeen-type model of electron states (BS), as nonlinear for Fermi-Dirac (FD) density of states describing two-dimensional electron gas at FE film surface, and as strongly nonlinear for Stephenson-Highland (SH) model used electrochemical analog of the Langmuir adsorption isotherm. Among considered BS, FD and SH models, the most various behavior of P-V- and Σ-V- loops is inherent to SH model.

Obtained results give new insight on the control of P-V- and Σ-V- loops temperature behaviour in FE thin films by interfacial screening mechanisms.