Coherent helix vacancy phonon and its ultrafast dynamics waning in topological Dirac semimetal Cd<sub>3</sub>As<sub>2</sub>
ORAL
Abstract
We report an ultrafast lattice dynamics investigation of the topological Dirac semimetal Cd3As2. A coherent phonon beating among three evenly spaced A1g optical phonon modes (of frequencies 1.80, 1.96, and 2.11 THz, respectively) is unambiguously observed. The two side modes originate from the counter helixes composing Cd vacancies. Significantly, such helix vacancy-induced phonon (HVP) modes experience prominent extra waning in their ultrafast dynamics as temperature increases, which is immune to the central mode. Above 200 K, the HVP becomes inactive, which may potentially affect the topological properties. Our results in the lattice degree of freedom suggest the indispensable role of temperature in considering topological properties of such quantum materials.
*This work was supported by the National Key Research and Development Program of China (Grants No.2016YFA0300300 and No. 2016YFA0401000), the National Basic Research Program of China (Grant No.2015CB921301), the National Natural Science Foundation of China (Grants No. 11574383, No. 11274372, No. 11274362,
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Presenters
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Fei Sun
- Insititute of Physics, Chinese Academy of Scienes (CAS)