High-Temperature Quantum Valley Hall Effect with Quantized Resistance and a Topological Switch

TL;DR

This paper demonstrates robust, quantized resistance plateaus in kink states of bilayer graphene at high temperatures, showcasing a topological switch with potential for quantum electronics.

Contribution

It reports the first observation of quantized resistance in quantum valley Hall kink states at zero magnetic field and high temperature, with a tunable topological switch.

Findings

Quantized resistance plateaus observed up to 50 Kelvin.

Electrical control of a topological switch with a 200 on/off ratio.

Robustness and tunability of kink states demonstrated.

Abstract

Edge states of a topological insulator can be used to explore fundamental science emerging at the interface of low dimensionality and topology. Achieving a robust conductance quantization, however, has proven challenging for helical edge states. Here we show wide resistance plateaus in kink states - a manifestation of the quantum valley Hall effect in Bernal bilayer graphene - quantized to the predicted value at zero magnetic field. The plateau resistance has a very weak temperature dependence up to 50 Kelvin and is flat within a dc bias window of tens of mV. We demonstrate the electrical operation of a topology-controlled switch with an on/off ratio of 200. These results demonstrate the robustness and tunability of the kink states and its promise in constructing electron quantum optics devices.