56 research outputs found
Non-adiabatic extension of the Zak phase and charge pumping in the Rice--Mele model
In this study, the Landau--Zener (LZ) transition method is applied to
investigate a weak non-adiabatic effect on the Zak phase and the topological
charge pumping in the Rice--Mele model. The non-adiabatic effect is formulated
using the LZ transfer matrix. The effective lower band wave function picks up
the Stokes phase as well as the usual dynamical phase through two avoided
crossings appearing in the two band instantaneous energy spectrum. The
interference effect from the upper band has a decisive influence on the decay
behavior of the lower band population. A non-adiabatic extension of the Zak
phase can then be formulated, corresponding to the center of mass of the lower
band Wannier function. Furthermore, we estimate the validity of the LZ
formalism and verify the breakdown of the quantization of the topological
charge pumping by changing the sweeping speed.Comment: 8 pages, 4 figures, accepted in EPJ
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