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Topological Circular Dichroism in Chiral Multifold Semimetals
1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Physical Review Letters
|September 29, 2023
Summary
Topological circular dichroism is unique to chiral multifold fermions, not Weyl fermions, due to emergent SO(3) symmetry. This distinct response was predicted in CoSi, highlighting unconventional fermion properties.
Area of Science:
- Condensed matter physics
- Quantum states
- Topological materials
Background:
- Nontrivial topology in quantum states is key in condensed matter physics.
- Topological circular dichroism is a phenomenon studied in materials with specific electronic structures.
Purpose of the Study:
- Investigate topological circular dichroism in chiral semimetals.
- Differentiate responses between Weyl fermions and chiral multifold fermions.
Main Methods:
- Utilized linear response theory.
- Performed first-principles calculations.
- Analyzed emergent SO(3) rotational symmetry and its selection rules.
Main Results:
- Topological circular dichroism is forbidden for Weyl fermions due to emergent SO(3) symmetry and combined particle-hole conjugation and spatial inversion.
- This dichroism is unique to chiral multifold fermions.
- Predicted topological circular dichroism in CoSi for photon energies below 0.2 eV.
Conclusions:
- Established a unique response property for unconventional fermions.
- Demonstrated that topological circular dichroism distinguishes chiral multifold fermions from Dirac and Weyl fermions.
- Motivated further research into unique responses of unconventional fermions.
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