Program

P.71 -- Poster, NCTP-42

Date: Wednesday, 2 August 2017

Time: 08h30 - 10h00

Excitonic condensation phase diagram in the extended Falicov-Kimball model with electron-phonon interaction

Do Thi Hong Hai (1,2,3) and Phan Van Nham (4)

(1) Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay, Hanoi, Vietnam; (2) Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Cau Giay, Hanoi, Vietnam; (3) Department of Physics, Hanoi University of Mining and Geology, Duc Thang, Bac Tu Liem, Hanoi, Vietnam; (4) Institute of Research and Development, Duy Tan University, 3 Quang Trung, Danang, Vietnam.

Influence of temperature on the excitonic condensation state in two-dimensional extended Falicov-Kimball model with electron-phonon interaction has been investigated by using the unrestricted Hartree-Fock approximation. Treating both the Coulomb interaction and the electron-phonon coupling in an equal footing, we analyze phase diagrams of the excitonic condensation state. At a given electron-phonon coupling, lowering temperature we find out a semimetal-excitonic condensate at a small Coulomb interaction and a semiconductor-excitonic condensate at a large Coulomb interaction. The excitonic condensate window is enlarged if the electron-phonon coupling is increased. A crossover from a BCS type to a BEC type of the excitonic condensation state driven either by the Coulomb interaction or the electron-phonon coupling in this systems at low temperature is also addressed.

Presenter: Do Thi Hong Hai