Probing electron-phonon and phonon-phonon coupling in type-II Dirac semi-metal NiTe2via temperature-dependent Raman spectroscopy

Minna Theres James; Shoubhik Mandal; Nirmal K Sebastian; Pramita Mishra; R Ganesan; P S Anil Kumar

doi:10.1088/1361-648X/acb18a

Probing electron-phonon and phonon-phonon coupling in type-II Dirac semi-metal NiTe₂via temperature-dependent Raman spectroscopy

J Phys Condens Matter. 2023 Jan 27;35(12). doi: 10.1088/1361-648X/acb18a.

Authors

Minna Theres James¹, Shoubhik Mandal¹, Nirmal K Sebastian², Pramita Mishra¹, R Ganesan¹, P S Anil Kumar¹

Affiliations

¹ Department of Physics, Indian Institute of Science, Bangalore, Karnataka 560012, India.
² Centre for Nanoscience and Engineering, Indian Institute of Science, Bangalore, Karnataka 560012, India.

PMID: 36623321
DOI: 10.1088/1361-648X/acb18a

Abstract

We report the temperature-dependent structural characterization of type-II Dirac semimetal NiTe₂in the form of a bulk single crystal and a nanoflake (200 nm thick). Detailed x-ray diffraction study along with Rietveld refinement analysis reveals superior crystallinity and linear thermal expansion coefficient (α_T) of 5.56 × 10^-6and 22.5 × 10^-6K^-1along a or b and c lattice directions, respectively. Temperature evolution of Raman spectra shows non-linear variations in the phonon frequency and full-width half maxima of the out-of-plane A1gand in-plane E_gmodes. Raman mode E2g1, corresponding to an in-plane vibration, disappears on decreasing the thickness from bulk to nanoflake. Quantitative analysis with anharmonic model yields dominating electron-phonon interaction over phonon-phonon interaction mediated by three- and four-phonon processes.

Keywords: Dirac semimetal; Raman spectroscopy; x-ray diffraction.