Program

O.23 -- Oral, NCTP-42

Date: Wednesday, 2 August 2017

Time: 16h00 - 16h20

Order-disorder phase transition in ultrathin ferroelectric perovskite films

Nguyen Tu Niem, Bach Thanh Cong

Faculty of Physics, VNU University of Science 334 Nguyen Trai, Hanoi, Vietnam

The order-disorder phase transition in ferroelectric films down to nanoscale thickness is usually explained within the framework of the famous Landau-Ginzburg-Devonshire theory. But for ultrathin films consisting from few atomic layers, the problem is still opened. In this report, the thermodynamic theory for the ultrathin ferroelectric perovskite films (UFPF) is developed using the Ising model in transverse field and mean field approximation. It is shown that, the polarization, entropy, specific heat phase transition temperature of the UFPF are strongly affected by the thickness and transverse field. Dependence of the critical thickness (thickness below that the ferroelectric order is destroyed) on the thickness and transversal field is also discussed and calculated for several UFPF.

Presenter: Nguyễn Từ Niệm