title: Spontaneous symmetry breaking and dynamic phase transition in monolayer silicene.
abstract: The (sqrt[3]×sqrt[3])R30° honeycomb of silicene monolayer on Ag(111) was found to undergo a phase transition to two types of mirror-symmetric boundary-separated rhombic phases at temperatures below 40 K by scanning tunneling microscopy. The first-principles calculations reveal that weak interactions between silicene and Ag(111) drive the spontaneous unusual buckling in the monolayer silicene, forming two energy-degenerate and mirror-symmetric (sqrt[3]×sqrt[3])R30° rhombic phases, in which the linear band dispersion near the Dirac point and a significant gap opening (150 meV) at the Dirac point were induced. The low transition barrier between these two phases enables them to be interchangeable through dynamic flip-flop motion, resulting in the (sqrt[3]×sqrt[3])R30° honeycomb structure observed at high temperature.
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Baojie
authors.initials: B
authors.lastname: Feng
authors.forename: Zijing
authors.initials: Z
authors.lastname: Ding
authors.forename: Jinglan
authors.initials: J
authors.lastname: Qiu
authors.forename: Peng
authors.initials: P
authors.lastname: Cheng
authors.forename: Kehui
authors.initials: K
authors.lastname: Wu
authors.forename: Sheng
authors.initials: S
authors.lastname: Meng