Time-Reversal-Breaking Weyl Fermions in Magnetic Heusler Alloys

Area of Science:

• Condensed matter physics
• Materials science
• Quantum materials

Background:

• Weyl fermions observed in time-reversal-invariant materials with broken inversion symmetry.
• Existing Weyl materials often have complex Fermi surfaces due to numerous Weyl nodes.
• Exotic transport properties like the chiral anomaly are predicted in Weyl systems.

Purpose of the Study:

• Predict a new class of Weyl fermion systems.
• Explore Weyl physics in magnetic materials with broken time-reversal symmetry.
• Identify materials with a minimal number of Weyl nodes for simplified study.

Main Methods:

• Theoretical prediction of Weyl fermions in magnetic Heusler materials (XCo2Z).
• Utilized an inversion invariant to guarantee Weyl fermion existence in centrosymmetric magnetic systems.
• Calculated electronic band structures and Fermi surfaces.

Main Results:

• Identified Co-based magnetic Heusler materials (XCo2Z) as a new family of Weyl systems.
• These materials possess an odd number of Weyl fermion pairs, with only two Weyl nodes at the Fermi level when alloyed.
• Weyl nodes are protected by rotational symmetry and exhibit large separation in the Brillouin zone.
• Calculated Fermi arcs corresponding to the Weyl nodes.

Conclusions:

• Co-based magnetic Heuslers provide a promising platform for studying magnetic Weyl physics.
• The minimal number of Weyl nodes simplifies the investigation of exotic transport properties.
• Offers a realistic experimental avenue for manipulating and understanding magnetic Weyl phenomena.