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We probe the possible double-Weyl state in cubic SrSi2 using optical spectroscopy. The complex optical conductivity was measured in a frequency range from 70 cm−1 to 22 000 cm−1 at temperatures down to 10 K at ambient pressure. The optical response of SrSi2 can be well separated into the intraband (free carriers) and interband contributions. Additionally, four infrared-active phonons are detected. As follows from the optical spectra, the free-carrier density decreases with decreasing temperature, consistent with an activation behaviour. Experimental interband conductivity juxtaposed with ab initio calculations shows that conventional density-functional theory fails to describe the electronic structure of SrSi2 in the vicinity of the Fermi level. A semi-local exchange-correlation potential allows a much better agreement with the experiment, resulting in the trivial (gapped) band structure of SrSi2. The direct gap estimated from the measurements is approximately 40 meV.

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  ©2025 American Physical Society

Keyword: silicide, semiconductor, optical conductivity

Date published: 2025-10-20

Publisher: American Physical Society (APS)

Journal:

• Physical Review B (ISSN: 24699950) vol. 112 issue. 15 155209

Funding:

• Deutsche Forschungsgemeinschaft DR228/51-3
• Japan Society for the Promotion of Science JP22H00268

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5822

First published URL: https://doi.org/10.1103/y1gj-67wz

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Updated at: 2025-10-24 08:30:08 +0900

Published on MDR: 2025-10-24 08:18:41 +0900