Programme

P.15 -- Poster, NCTP-43

Date: Tuesday, 31 July 2018

Time: 08:30 - 10:00

Phase diagram of excitonic condensation state in transition metal dichalcogenides

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, 18 Hoang Quoc Viet, 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.

The excitonic condensation state in transition metal dichalcogenides has been investigated by applying the unrestricted Hartree-Fock approximation to two-dimensional extended Falicov-Kimball model including electron-phonon interaction. Treating both the Coulomb attraction and the electron-phonon coupling in an equal footing, we have derived a set of self-consistent equations which allow us to determine both the excitonic condensate order parameter. Phase structures show us that both the Coulomb interaction and the electron-phonon coupling act together in establishing the excitonic condensed phase. At a given low temperature, the condensate phase is found in between two critical values of the Coulomb interaction. A critical temperature of the condensate phase transition increases as increasing the electron-phonon interaction. Depending on temperature and the Coulomb interaction, BCS-BEC crossover of the excitonic condensation state in the systems has been established.

Presenter: Do Thi Hong Hai