Tunable Topological States in Electron-Doped HTT-Pt

TL;DR

This paper demonstrates that electron doping in the organometallic framework HTT-Pt induces multiple topological phase transitions, switching from a normal insulator to quantum spin Hall and quantum anomalous Hall states, with sizable band gaps suitable for high-temperature applications.

Contribution

It is the first to show electron doping induces multiple topological phases in HTT-Pt, a synthesized organometallic material, including QSH and QAH states with large band gaps.

Findings

Electron doping causes phase transition from insulator to QSH state.

High doping breaks TRS, leading to QAH state.

Topologically nontrivial band gap up to 44.5 meV.

Abstract

Driving existing materials to exhibit topologically nontrivial state is of both scientific and technological interests. Using first-principle calculations, we propose the first demonstration of electron doping induced multiple quantum phase transition in a single material of the organometallic framework, HTT-Pt, which has been synthesized by reacting triphenylene hexathiol molecules (HTT) with PtCl2. At low elec-tron doping, the HTT-Pt converts from a normal insulator to a quantum spin Hall (QSH) insulator with time-reversal symmetry (TRS). At high electron doping, the TRS is further broken making the HTT-Pt a quantum anomalous Hall (QAH) insulator. The topologically nontrivial band gap of the electron-doped HTT-Pt opened by intrinsic spin-orbit coupling (SOC) can be as large as 44.5 meV, which is promising for realizing these quantum phases at high temperatures. The possibility of switching between the QSH and QAH states offers an intriguing platform for new device paradigm by interfacing between a QSH and QAH state.