Xing Bo, Chiu Wei-Ting, Poletti Dario, Scalettar R T, Batrouni George
Science, Mathematics and Technology Cluster, Singapore University of Technology and Design, 8 Somapah Road, 487372 Singapore.
Department of Physics, University of California, Davis, California 95616, USA.
Phys Rev Lett. 2021 Jan 8;126(1):017601. doi: 10.1103/PhysRevLett.126.017601.
Over the past several years, a new generation of quantum simulations has greatly expanded our understanding of charge density wave phase transitions in Hamiltonians with coupling between local phonon modes and the on-site charge density. A quite different, and interesting, case is one in which the phonons live on the bonds, and hence modulate the electron hopping. This situation, described by the Su-Schrieffer-Heeger (SSH) Hamiltonian, has so far only been studied with quantum Monte Carlo in one dimension. Here we present results for the 2D SSH model, show that a bond ordered wave (BOW) insulator is present in the ground state at half filling, and argue that a critical value of the electron-phonon coupling is required for its onset, in contradistinction with the 1D case where BOW exists for any nonzero coupling. We determine the precise nature of the bond ordering pattern, which has hitherto been controversial, and the critical transition temperature, which is associated with a spontaneous breaking of Z_{4} symmetry.
在过去几年中，新一代量子模拟极大地扩展了我们对哈密顿量中电荷密度波相变的理解，该哈密顿量存在局域声子模式与在位电荷密度之间的耦合。一个截然不同且有趣的情况是声子存在于键上，从而调制电子跳跃。这种由苏-施里弗-黑格（SSH）哈密顿量描述的情况，到目前为止仅在一维中通过量子蒙特卡罗方法进行了研究。在此，我们给出二维SSH模型的结果，表明在半填充时基态存在键序波（BOW）绝缘体，并认为其出现需要电子-声子耦合的临界值，这与一维情况相反，在一维中对于任何非零耦合BOW都存在。我们确定了键序模式的精确性质，这一点迄今存在争议，以及与(Z_{4})对称性自发破缺相关的临界转变温度。
