High-Chern-number and high-temperature quantum Hall effect without Landau levels

Abstract

The quantum Hall effect (QHE) with quantized Hall resistance of h/ νe ² started the research on topological quantum states and laid the foundation of topology in physics. Since then, Haldane proposed the QHE without Landau levels, showing nonzero Chern number | C| = 1, which has been experimentally observed at relatively low temperatures. For emerging physics and low-power-consumption electronics, the key issues are how to increase the working temperature and realize high Chern numbers ( C > 1). Here, we report the experimental discovery of high-Chern-number QHE ( C = 2) without Landau levels and C = 1 Chern insulator state displaying a nearly quantized Hall resistance plateau above the Néel temperature in MnBi ₂Te ₄ devices. Our observations provide a new perspective on topological matter and open new avenues for exploration of exotic topological quantum states and topological phase transitions at higher temperatures.

Abstract

We report the experimental discovery of high-Chern-number (C = 2) quantum Hall effect without Landau levels and C = 1 Chern insulator state above the Néel temperature in MnBi ₂Te ₄ devices.