Topological and magnetic phase transition in silicene-like zigzag nanoribbons

TL;DR

This paper explores the interplay of spin-orbital and Coulomb interactions in silicene-like zigzag nanoribbons, revealing phase transitions between topological insulators and magnetic states influenced by material parameters and external fields.

Contribution

It systematically analyzes the combined effects of spin-orbital interactions and Coulomb interactions on phase transitions in zigzag silicene nanoribbons, including the discovery of a double topological/magnetic phase transition.

Findings

Transition from band insulator to topological insulator when SOI or ribbon width exceeds critical values.

Magnetic phase transitions driven by exchange or electric fields in Hubbard-dominated systems.

Observation of a double topological/magnetic phase transition before phases are destroyed by strong electric fields.

Abstract

Spin-orbital interactions (SOI) in silicene results in the quantum spin Hall effect, while the Hubbard-induced Coulomb interaction in zigzag nanoribbons often generates a band gap with the anti-ferromagnetic (AF) spin orders on two edges. In this paper we systematically study these two joint contributions to the zigzag silicene-like nanoribbons (zSiNR). Some topological and magnetic phase transitions are investigated with different material parameters and external fields. We find when the ribbon width or the SOI value exceeds some critical value, the SOI may overcome the Coulomb interaction and the system transits from a band insulator to a topological insulator: the quantum-spin-Hall or the spin quantum-anomalous Hall state. We also find some magnetic phase transition exist in the Hubbard-dominated zSiNR systems when the exchange field or the electric field goes beyond some critical values. At last we observe a double topological/magnetic phase transition in a Hubbard-SOI-balanced zSiNR system before the magnetic and topological phases are destroyed by a strong electric field.