Large quantum anomalous Hall effect in spin-orbit proximitized rhombohedral graphene

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Phenomena

Background:

• The quantum anomalous Hall effect (QAHE) is a significant topological phenomenon characterized by quantized Hall resistance without an external magnetic field.
• Existing QAHE systems often rely on magnetic elements or moiré superlattices, limiting material choices and design flexibility.

Purpose of the Study:

• To investigate the emergence of QAHE in a non-magnetic, non-moiré heterostructure composed of rhombohedral pentalayer graphene and monolayer tungsten disulfide.
• To explore the underlying mechanisms, including electron correlation and spin-orbit coupling, responsible for the observed QAHE.

Main Methods:

• Fabrication of a rhombohedral pentalayer graphene-monolayer tungsten disulfide heterostructure.
• Experimental characterization of electrical transport properties, including Hall resistance measurements at low temperatures (up to 1.5 K) and zero magnetic field.

Main Results:

• Observation of the quantum anomalous Hall effect (QAHE) in the synthesized heterostructure at charge neutrality.
• Quantized Hall states with Chern numbers C = ±5 were identified.
• The QAHE was observed at temperatures up to approximately 1.5 Kelvin.

Conclusions:

• The study successfully demonstrates QAHE in a novel 2D material system without magnetic doping or moiré patterns.
• The observed large QAHE is attributed to the interplay of electron correlation in graphene's flat bands, gate-tuning, and proximity-induced spin-orbit coupling.
• This work highlights the potential of crystalline 2D materials for exploring complex topological physics and engineering exotic quantum states like chiral Majorana edge states.