Symmetry-enforced band topology observed in TiAs single crystals
Researchers grew stoichiometric hexagonal TiAs single crystals by chemical vapour transport and combined spectroscopy, ARPES, transport measurements and calculations. Four Raman-active vibrational modes were observed, while calculations indicated symmetry-protected topological band crossings.
Source review period: 2026-10-09
Published: · Updated:
The source does not state the event date; the period shown is the source review period.
To grow high-purity TiAs single crystals, the team used iodine-assisted chemical vapour transport from a polycrystalline precursor. X-ray diffraction and energy-dispersive spectroscopy checked structure and composition; Raman measurements examined vibrational modes, while angular magnetotransport probed directional response. ARPES data were compared with calculated three-dimensional bands.
Polarized Raman spectroscopy identified four Raman-active modes consistent with hexagonal symmetry. ARPES and first-principles calculations indicated symmetry-protected degeneracies at the Brillouin-zone boundary and a Van Hove saddle point about 0.5 eV below the Fermi level. Measured angular magnetoresistance showed twofold anisotropy. The results establish TiAs as a topological-semimetal research platform, not a device demonstration.
Data
Measurements reported by the study
The table reports only findings within this study’s experimental or model scope.
| Raman-active optical phonon modes identified | 4 | A1g, E1g and two E2g modes assigned in polarized Raman measurements on experimental TiAs crystals, consistent with calculations. |
Methodology
Quantity and scope are taken from the methods and results of the first arXiv version dated 9 October 2026; they should not be generalized beyond the study.
Updated:
Subjects and places
Subject proposals
- TransportSuggested
- Subject suggested from the title or summary: transportarxiv.org ↗
- Science and technologySuggested
- Preserved editorial category/topic; broad candidate onlyarxiv.org ↗
Geographic references
Only source-provided geographic references are shown. Opening an external map is optional. Optional story maps use OpenStreetMap. Opening a map sends your IP address and this site’s address to the map provider; location data remains readable as text without loading the map.
- China · Place role: Coverage · Place type: Country or area · Location precision: RegionalEvidence
- Explicit preserved editorial country/region; no city or national centroid inferredarxiv.org ↗