Anisotropic Fano resonance in the Weyl semimetal candidate LaAlSi
Journal
Physical Review B
Journal Volume
102
Journal Issue
23
Start Page
235162
ISSN
24699950
24699969
Date Issued
2020
Author(s)
Zhang, Kunyan
Wang, Tong
Pang, Xiaoqi
Han, Fei
Shang, Shun-Li
Liu, Zi Kiu
Li, Mingda
Saito, Riichiro
Huang, Shengxi
Abstract
Topological Weyl semimetal (WSM) is a solid-state realization of chiral Weyl fermions, whose phonon behaviors provide in-depth knowledge of their electronic properties. In this work, anisotropic Fano resonance is observed in a type-II WSM candidate LaAlSi by polarized Raman spectroscopy. The asymmetric line shape occurs for the B12 phonon mode of LaAlSi only for 488- and 532-nm laser excitations but not for 364-, 633-, and 785-nm excitations, suggesting the excitation selectivity. The asymmetry, frequency, and linewidth of the B12 phonon mode, along with the spectral background, all show fourfold rotational symmetry as a function of the polarization angle in the polarized Raman spectra. While the shift of Raman frequency in a metal or semimetal is typically attributed to Kohn anomaly, here we show that the anisotropic frequency shift in LaAlSi cannot be explained by the effect of Kohn anomaly, but potentially by the anisotropic scattering background of Fano resonance. Origins of the excitation-energy dependence and anisotropic behavior of the Fano resonance are discussed by the first-principles calculated electronic band structure and phonon dispersion.
Subjects
Aluminum Compounds
Anisotropy
Electronic Properties
Lanthanum Compounds
Laser Excitation
Lattice Vibrations
Phonons
Raman Spectroscopy
Silicon
Silicon Compounds
Anisotropic Behaviors
Anisotropic Scattering
Electronic Band Structure
Phonon Dispersions
Polarized Raman Spectra
Polarized Raman Spectroscopy
Rotational Symmetries
State Realizations
Resonance
SDGs
Publisher
American Physical Society
Type
journal article