Charge Density Wave Super Modes and Symmetry Breaking in Ultrathin Transition Metal Di Chalcogenides

Light matter interactions provide significant information about the quantum phenomena in the materials. One of the interesting quantum phenomena is Charge density wave (CDW), where the periodic modulation of the electronic charge density is accompanied by the lattice distortion, electronic instability with high anharmonicity.[4-5] The reconstruction of the lattice leads to folding of Brillouin zone along with the emergence of collective modes and enhanced multi body interactions.[4, 6, 7]

 

Dr. Soni will discuss the CDW in materials and interesting aspects of Raman modes observed in thickness dependence of CDW in layered 2H-TaS2 and multiphonon interactions. Bulk 2H-TaS2 endures a CDW transition at ∼ 76 K, however the onset of CDW instability in can exist up to 200 K due to breaking of translational and center of inversion symmetry. Interestingly, the CDW transition temperature has inverse relation with the thickness of atomically thin layers. [6-7] In this talk he will also elaborate on their recent work on unique optical properties and light-matter interactions in the chalcogenide materials for optoelectronics, charge density waves and thermoelectric research.

 

References:

 

1. D. Rawat, A. Singh, N. K. Singh and A. Soni, Phys Rev B 197, 155203 (2023),

2. D. Rawat, A. Thomas, Ajay P S Rana, C. Bera and A. Soni, Phys Rev B (2024).

3. J. Pandey and A. Soni, Phys Rev Res. 02, 033118 (2020).

4. D. Rawat, J. Pandey, S, Menon, U. V. Waghmare and A. Soni, arXiv:2311.02371 (2023).

5. P. Dutta, S. Chandra, I. Maria, K. Debnath, D. Rawat, A. Soni, U. V. Waghmare and K. Biswas, Adv. Funct. Mater. 2312663 (2023).

6. K. S. Rana, D. Sarkar, N. Pandey, A. Singh, C. Bera, K. Biswas and A. Soni, Phys Rev B 109, 115202 (2024),

7. A. Kashyap, D. Rawat, D. Sarkar, N.K. Singh, K. Biswas and A. Soni, Angewandte Chemie, International Edition, 202401234 (2024).