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Updated: Sep 19, 2025
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High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
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Unconventional Topological Weyl Dipole Phonon.
Jianhua Wang1,2, Yang Wang3, Feng Zhou1
1Institute of Quantum Materials and Devices, Tiangong University, Tianjin, 300387, China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|June 17, 2025
Summary
Researchers discovered a new topological state, the unconventional Weyl dipole (WD), in Y(OH)3. This novel phase exhibits unique surface and hinge states protected by topological charges and quantized quadrupole moments.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Topological Materials
Background:
- Weyl points (WPs) with opposite topological charges can form Z2 Weyl dipoles (WDs).
- Realizing topological Weyl dipole (TWD) phases in crystalline materials is challenging.
- WDs are expected to appear in pairs and resist annihilation.
Purpose of the Study:
- To demonstrate the existence of a nontrivial unconventional WD phase in crystalline materials.
- To investigate the properties and protection mechanisms of this novel topological phase.
Main Methods:
- First-principles calculations.
- Theoretical analysis of phonon spectra.
- Characterization of topological charges and quadrupole moments.
Main Results:
- The nontrivial unconventional WD phase was identified in the phonon spectra of P63 type Y(OH)3.
- This unconventional WD is protected by a quantized quadrupole moment.
- It consists of one unconventional charge-3 WP and three conventional charge-1 WPs.
- Unique 2D sextuple-helicoid Fermi-arc surface states and 1D hinge states were observed.
Conclusions:
- Y(OH)3 hosts a novel nontrivial unconventional WD phase.
- The findings provide a material realization for TWD phases.
- The observed topological states are robustly protected by topological charges and quantized quadrupole moments.
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