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arXiv · 1906.03675

Pfaffian formalism for higher-order topological insulators

Heqiu Li·Kai Sun
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Abstract

We generalize the Pfaffian formalism, which has been playing an important role in the study of time-reversal invariant topological insulators (TIs), to 3D chiral higher-order topological insulators (HOTIs) protected by the product of four-fold rotational symmetry $C_4$ and the time-reversal symmetry $T$. This Pfaffian description reveals a deep and fundamental link between TIs and HOTIs, and allows important conclusions about TIs to be generalized to HOTIs. As examples, we demonstrate in the Letter how to generalize Fu-Kane's parity criterion for TIs to HOTIs, and also present a general method to efficiently compute the $Z_2$ index of 3D chiral HOTIs without a global gauge.

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Heqiu Li, Kai Sun. 2020-07-22. Pfaffian formalism for higher-order topological insulators. https://doi.org/10.1103/physrevlett.124.036401

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