Abstract
We investigate a tight-binding model on a two-dimensional square lattice with three terms: the Rashba spin–orbit coupling, the real amplitude next-nearest spin–orbit coupling, and an exchange field. We calculate the first Chern number to identify band topology. It is found that the Chern number takes the quantized values of C1 = 1, 2 and the chiral edge modes can be obtained. Therefore our model realizes the quantum anomalous Hall (QAH) effect. The Rashba coupling is positive for the QAH phase while the next-nearest coupling is detrimental to it. By increasing the exchange field intensity, the Chern number changes from quantized value 2 to 0. The behavior of the edge states is also studied. Particularly for C1 = 2 case, there are two gapless spin-polarized edge states with the same spin polarization moving in the same spatial direction. This indicates that their appearance is topological rather than accidental.
Published Version
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