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arXiv · 2207.04026

Fractional second-order topological insulator from a three-dimensional coupled-wires construction

Katharina Laubscher·Pim Keizer·Jelena Klinovaja
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Abstract

We construct a three-dimensional second-order topological insulator with gapless helical hinge states from an array of weakly tunnel-coupled Rashba nanowires. For suitably chosen interwire tunnelings, we demonstrate that the system has a fully gapped bulk as well as fully gapped surfaces, but hosts a Kramers pair of gapless helical hinge states propagating along a path of hinges that is determined by the hierarchy of interwire tunnelings and the boundary termination of the system. Furthermore, the coupled-wires approach allows us to incorporate electron-electron interactions into our description. At suitable filling factors of the individual wires, we show that sufficiently strong electron-electron interactions can drive the system into a fractional second-order topological insulator phase with hinge states carrying only a fraction $e/p$ of the electronic charge $e$ for an odd integer $p$.

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Katharina Laubscher, Pim Keizer, Jelena Klinovaja. 2023-01-26. Fractional second-order topological insulator from a three-dimensional coupled-wires construction. https://doi.org/10.1103/physrevb.107.045409

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