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

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• The quantum Hall effect (QHE) established the field of topological quantum states, with quantized Hall resistance h/νe².
• Haldane's model introduced QHE without Landau levels (Chern number |C|=1), observed at low temperatures.
• Increasing working temperatures and achieving high Chern numbers (C>1) are crucial for future electronics.

Purpose of the Study:

• To experimentally discover high-Chern-number QHE states without Landau levels.
• To investigate topological quantum states and phase transitions at higher temperatures.

Main Methods:

• Fabrication and characterization of MnBi2Te4 devices.
• Measurement of Hall resistance and identification of topological states.
• Temperature-dependent measurements above the Néel temperature.

Main Results:

• Experimental discovery of QHE with C=2 and a Chern insulator state with C=1 in MnBi2Te4.
• Observation of nearly quantized Hall resistance plateaus above the Néel temperature.
• Demonstration of topological states persisting at elevated temperatures.

Conclusions:

• The findings present a new platform for high-Chern-number topological states without Landau levels.
• This work opens avenues for exploring exotic topological quantum phenomena at higher temperatures.
• The results have implications for developing next-generation low-power electronic devices.