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Coherent optical phonon oscillation and possible electronic softening in WTe2 crystals.

ABSTRACT: A rapidly-growing interest in WTe2 has been triggered by the giant magnetoresistance effect discovered in this unique system. While many efforts have been made towards uncovering the electron- and spin-relevant mechanisms, the role of lattice vibration remains poorly understood. Here, we study the coherent vibrational dynamics in WTe2 crystals by using ultrafast pump-probe spectroscopy. The oscillation signal in time domain in WTe2 has been ascribed as due to the coherent dynamics of the lowest energy A1 optical phonons with polarization- and wavelength-dependent measurements. With increasing temperature, the phonon energy decreases due to anharmonic decay of the optical phonons into acoustic phonons. Moreover, a significant drop (15%) of the phonon energy with increasing pump power is observed which is possibly caused by the lattice anharmonicity induced by electronic excitation and phonon-phonon interaction.

SUBMITTER: He B

PROVIDER: S-EPMC4960623 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Coherent optical phonon oscillation and possible electronic softening in WTe2 crystals.

He Bin B Zhang Chunfeng C Zhu Weida W Li Yufeng Y Liu Shenghua S Zhu Xiyu X Wu Xuewei X Wang Xiaoyong X Wen Hai-Hu HH Xiao Min M

Scientific reports 20160726

A rapidly-growing interest in WTe2 has been triggered by the giant magnetoresistance effect discovered in this unique system. While many efforts have been made towards uncovering the electron- and spin-relevant mechanisms, the role of lattice vibration remains poorly understood. Here, we study the coherent vibrational dynamics in WTe2 crystals by using ultrafast pump-probe spectroscopy. The oscillation signal in time domain in WTe2 has been ascribed as due to the coherent dynamics of the lowest ...[more]

PMID: 27457385

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