Half-integer quantized anomalous thermal Hall effect in the Kitaev material candidate α-RuCl₃

Area of Science:

• Condensed Matter Physics
• Quantum Materials
• Topological Phases of Matter

Background:

• Two-dimensional (2D) materials offer unique platforms for exploring exotic quantum phenomena.
• Honeycomb materials like α-RuCl₃ are candidates for realizing Kitaev spin liquid states.
• Topological quantum phenomena, such as the quantum Hall effect, are of significant scientific interest.

Purpose of the Study:

• To investigate the nature of thermal quantum Hall conductance in α-RuCl₃.
• To determine if half-integer quantized thermal Hall conductance occurs without an out-of-plane magnetic field.
• To explore the relationship between observed phenomena and topological orders.

Main Methods:

• Experimental measurement of thermal Hall conductance in α-RuCl₃ under varying magnetic field orientations.
• Analysis of the field-angular dependence of the quantized thermal Hall conductance.
• Comparison of experimental results with theoretical predictions for topological Chern numbers.

Main Results:

• Observation of a half-integer thermal quantum Hall conductance plateau in α-RuCl₃.
• The plateau persists even when the magnetic field has no out-of-plane component.
• The field-angular variation matches the sign structure of the topological Chern number for a pure Kitaev spin liquid.

Conclusions:

• The findings suggest the presence of non-Abelian topological order in α-RuCl₃.
• This topological order persists despite the presence of non-Kitaev interactions.
• The results provide strong evidence for fractionalization of local magnetic moments in this material.