Time-reversal symmetry breaking type-II Weyl state in YbMnBi₂

Area of Science:

• Condensed-matter physics
• High-energy physics
• Materials science

Background:

• Dirac and Weyl fermions are crucial for fundamental physics and technological applications.
• Detecting magnetic Weyl semimetals experimentally remains a challenge.
• Existing research has established Dirac and noncentrosymmetric Weyl fermions in various materials.

Purpose of the Study:

• To experimentally detect time-reversal symmetry breaking in magnetic Weyl semimetals.
• To design and investigate novel materials exhibiting Weyl states.
• To establish a link between high-energy and condensed-matter physics through experimental observation.

Main Methods:

• Material design and synthesis.
• Magnetization and magneto-optical microscopy for characterizing magnetic properties.
• Angle-resolved photoemission spectroscopy (ARPES) for direct observation of electronic states.

Main Results:

• Experimental and theoretical evidence for a time-reversal symmetry breaking Weyl state in YbMnBi2.
• Observation of canted antiferromagnetism modeling the time-reversal symmetry breaking.
• Direct spectroscopic observation of two pairs of Weyl points connected by Fermi arcs using ARPES.

Conclusions:

• YbMnBi2 realizes a magnetic Weyl semimetal state.
• The study provides a direct experimental link between high-energy and condensed-matter physics.
• Demonstrates a practical approach for designing materials with exotic electronic properties.