Raman scattering study of large magnetoresistance semimetals TaAs${}_2$ and NbAs${}_2$

Abstract

We have performed polarized and temperature-dependent Raman scattering measurements on extremely large magnetoresitance compounds TaAs${}_2$ and NbAs${}_2$. In both crystals, all the Raman active modes, including six A${}_g$ modes and three B${}_g$ modes, are clearly observed and well assigned with the combination of symmetry analysis and first-principles calculations. The well-resolved periodic intensity modulations of the observed modes with rotating crystal orientations, verify the symmetry of each assigned mode and are fitted to experimentally determine the elements of Raman tensor matrixes. The broadening of two A${}_g$ modes seen in both compounds allows us to estimate electron-phonon coupling constant, which suggests a relatively small electron-phonon coupling in the semimetals TaAs${}_2$ and NbAs${}_2$. The present study provides the fundamental lattice dynamics information on TaAs${}_2$ and NbAs${}_2$ and may shed light on the understanding of their extraordinary large magnetoresistance.

References in corpus (6)

• Titanic Magnetoresistance in WTe2
• Electronic structure basis for the titanic magnetoresistance in WTe${}_2$
• Quantum oscillations, thermoelectric coefficients and the Fermi surface of semi-metallic WTe2
• Anisotropic giant magnetoresistance in NbSb2
• Phonon anomalies in pure and underdoped R{1-x}K{x}Fe{2}As{2} (R = Ba, Sr) investigated by Raman light scattering
• Evidence of superconductivity-induced phonon spectra renormalization in alkali-doped iron selenides