Optical conductivity of topological semimetal Nb$_{2n+1}$Si$_n$Te$_{4n+2}$
TLDR
This paper analyzes the anisotropic optical conductivity of Nb-Si-Te topological semimetals, revealing distinct intraband and interband behaviors.
Key contributions
- Analyzes optical conductivity of Nb-Si-Te topological semimetals with quasi-one-dimensional nodal-line states.
- Reveals anisotropic Drude weight: finite along nodal-line direction, vanishes quadratically transverse.
- Finds interband conductivity has linear frequency dependence with a direction-dependent slope.
- Demonstrates zero-temperature conductivity results remain valid at experimentally relevant temperatures.
Why it matters
This paper provides crucial insights into the fundamental optical properties of Nb-Si-Te, a family of topological semimetals. Understanding their anisotropic conductivity is vital for potential applications in optoelectronics and quantum computing, especially given their dimensionality-tunable nature. The findings validate theoretical predictions across relevant temperatures.
Original Abstract
We study the linear optical conductivity of the Nb$_{2n+1}$Si$_n$Te$_{4n+2}$ family of layered van der Waals materials, which has recently gained considerable attention owing to its dimensionality-tunable electronic structure with a quasi-one-dimensional nodal-line state. At zero temperature, we analytically show that the Drude weight exhibits strong anisotropy: along the nodal-line direction it is finite at charge neutrality, whereas in the transverse direction it vanishes quadratically with Fermi energy. On the other hand, the interband optical conductivity exhibits the same linear frequency dependence along both the longitudinal and transverse directions, with only a direction-dependent slope in the low-frequency regime. We further analyze the leading finite-temperature corrections to the intraband and interband optical conductivities, showing that the zero-temperature results remain valid up to experimentally relevant temperatures.
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