期刊
PHYSICAL REVIEW B
卷 79, 期 19, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevB.79.195321
关键词
ground states; metal-insulator transition; spin Hall effect; wave functions
We study the phases of Bloch insulators with time-reversal symmetry on the basis of the homotopy of the ground-state wave functions in momentum space and find that there are two topological classes characterized by a Z(2) invariant. The results are in agreement with a recent study based on counting the zeroes of a certain Pfaffian function related to the ground-state wave function. It is shown that there is a link between the formulation of the topological invariant presented here and the number of robust edge states. A formula is also provided which greatly simplifies the computation of the invariant in a large number of cases. The present study provides guidance for the search of systems which belong to the nontrivial topological class and also establishes a link between the quantum spin Hall effect and the integer quantum Hall effect.
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