Anomalous phonon-mode dependence in polarized Raman spectroscopy of the topological Weyl semimetal TaP
Journal
Physical Review B
Journal Volume
101
Journal Issue
1
Start Page
014308
ISSN
24699950
24699969
Date Issued
2020
Author(s)
Zhang, Kunyan
Pang, Xiaoqi
Wang, Tong
Han, Fei
Shang, Shun-Li
Nugraha, Ahmad R.T.
Liu, Zi Kiu
Li, Mingda
Saito, Riichiro
Abstract
Topological Weyl semimetals (WSMs) have attracted widespread interest due to the chiral Weyl fermions and surface Fermi arcs that enable unique optical and transport phenomena. In this work, we present angle-resolved Raman spectroscopy of TaP, a prototypical noncentrosymmetric WSM, for five excitation wavelengths ranging from 364 to 785 nm. The Raman-active modes, A1, B11, and B12 modes, exhibit two main unique features beyond the conventional Raman theory. First, the relative intensities of Raman-active modes change as a function of the excitation wavelength. Second, angle-resolved polarized Raman spectra show systematic deviation from the Raman tensor theory. In particular, the B11 mode is absent for 633-nm excitation, whereas the B12 mode shows an unusual twofold symmetry instead of a fourfold symmetry for 488-, 532-, and 633-nm excitations. These unconventional phenomena are attributed to the interference effect in the Raman process owing to the existence of multiple carrier pockets with almost the same energy but different symmetries.
Subjects
Topology
Excitation Wavelength
Interference Effects
Non-centrosymmetric
Polarized Raman Spectra
Polarized Raman Spectroscopy
Raman Active Modes
Systematic Deviation
Transport Phenomena
Raman Spectroscopy
SDGs
Publisher
American Physical Society revtex@aps.org
Type
journal article