Optical conductivity of triple point fermions

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Non-symmorphic lattices host exotic electronic states, including triple point fermions.
• Understanding the optical properties of these states is crucial for their experimental identification and application.

Purpose of the Study:

• To investigate the optical absorption properties of generic triple point fermion systems.
• To identify unique optical signatures that distinguish triple point fermions from Dirac/Weyl fermions.

Main Methods:

• Analysis of a generic triple point fermion Hamiltonian parameterized by an angular parameter, λ.
• Calculation of Drude and interband optical absorption spectra.
• Comparison of optical responses with Dirac/Weyl fermion systems.

Main Results:

• Strong dependence of optical absorption on the parameter λ was observed.
• The T² coefficient of the Drude weight shows deviations from Dirac/Weyl fermions, providing a distinguishing feature.
• A specific point (λ = π/6) exhibits zero helicity reversal, which emerges upon deviation from this point.

Conclusions:

• Optical absorption measurements can effectively differentiate triple point degeneracies from Dirac/Weyl degeneracies.
• The parameter λ significantly influences the electronic and optical properties of triple point fermion systems.
• Helicity reversal transitions serve as a sensitive probe of the electronic structure in these systems.