Investigation of Light Harvesting and Magnetic Quantum Materials Using Ultrafast and Terahertz Spectroscopy

Mukherjee, Soumya (2024) Investigation of Light Harvesting and Magnetic Quantum Materials Using Ultrafast and Terahertz Spectroscopy. PhD thesis, Indian Institute of Science Education & Research Kolkata.

Text (PhD thesis of Soumya Mukherjee (17RS025)) 17RS025.pdf - Submitted Version Restricted to Repository staff only Download (19MB)

Abstract

Probing condensed matter systems using femtosecond pulsed lasers has become one of the most advanced techniques in contemporary experimental physics. The works presented in this thesis are the experimental studies of different condensed matter systems where the major experimental techniques are femtosecond laser based. More specifically, time domain terahertz spectroscopy and ultrafast pump-probe spectroscopy technique have been employed to probe condensed matter systems here. Steady state terahertz optical properties have been measured using time domain terahertz spectroscopy, whereas non-degenerate pump-probe technique is used to explore the photo-excited carrier dynamics down to sub-picosecond time resolution. In accordance with their utility, these two tools have been employed in resolving specific problems related to various condensed matter systems. The list of condensed systems under investigation here is diverse, which includes magnetic quantum materials, transition-metal dichalcogenide, hole-plsmonic nanomaterials and polymer composites. THz-TDS studies of magnetic topological insulators, MnBi₂Te₄ and Sb doped MnBi₂Te₄ are found to reveal the influence of magnetic ordering on their electronic band structure. Optical pump-probe studies of CuS and MoSe2, and detailed analysis of the corresponding decay dynamics are found to be instrumental in understanding their photocatalytic efficiency. The polymer-metal composite film PVA-GO-Ag shows considerable THz shielding efficiency and intriguing THz conductivity features in their THz-TDS studies. These studies in this thesis work suggests the utmost importance of THz-TDS and optical pump-probe measurements in exploring intriguing physics as well as characterizing application prospects of condensed matter systems.

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