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Ultrafast interactions with electromagnetic pulses—from femtosecond optical to terahertz (THz)
regimes—offer a powerful lens into the dynamic behavior of quantum materials. In this talk, I will
present our group’s efforts to harness these techniques to uncover and manipulate collective
excitations in layered magnetic and topological systems. Using femtosecond pump–probe and THz
time-domain spectroscopy, we explore how spins, excitons, and lattice vibrations interact on their
intrinsic timescales. I will highlight key results on CrSiTe₃ [1], where photoinduced strain reveals a
magnetic dimensional crossover, and on NiPS₃ [2], where spin–orbit–entangled excitons couple
dynamically to magnetic order. I will also discuss studies on BiSbTe₁.₅Se₁.₅ [3] and MnBi₂Te₄
[4], which reveal how topological surface states interact with phonons and magnetic phases under
ultrafast and THz excitation. Collectively, these studies demonstrate how light can both probe and
control fundamental interactions in correlated quantum materials, opening new pathways toward
optically driven quantum and spintronic functionalities.
References:
1. "Probing of magnetic dimensional crossover in CrSiTe3 through picosecond strain pulses", Anjan
Kumar N M, Soumya Mukherjee, Abhirup Mukherjee, Ajinkya Punjal, Shubham Purwar,
Thirupathaiah Setti, Shriganesh Prabhu S, Siddhartha Lal, N. Kamaraju, Phys. Rev. B 111, L140414
(2025).
2. "Ultrafast Dynamics of Spin-Orbit Entangled Excitons Coupled to Magnetic Ordering in van der
Waals Antiferromagnet NiPS₃ ", Sidhanta Sahu, Anupama Chauhan, Poulami Ghosh, Sayan Routh,
Ruturaj Puranik, Setti Thirupathaiah, Siddhartha Lal, Shriganesh Prabhu S., Chiranjib Mitra, and N.
Kamaraju, arXiv:2509.04900 (2025). (Submitted and under review).
3. "Ultrafast dynamics of carriers, coherent acoustic phonons and strain pulses in BiSbTe1.5Se1.5
topological insulator thin films", Anupama Chauhan, Sidhanta Sahu, Poulami Ghosh, Dheerendra
Singh, Sambhu G Nath, Anjan Kumar N M, P.K. Panigrahi, Chiranjib Mitra, N. Kamaraju, Phys. Rev.
B 112, 054311 (2025).
4. "Investigation of magnetic order influenced phonon and electron dynamics in MnBi2Te4 and Sb
doped MnBi2Te4 through terahertz time-domain spectroscopy ", Soumya Mukherjee, Anjan Kumar
NM, Subhadip Manna, Sambhu G Nath, Radha Krishna Gopal, Chiranjib Mitra, N. Kamaraju, Phys.
Rev. B 110, 195401 (2024). |