My current interest is primarily around exploring elementary phenomena and analogies in a couple of very old and well-studied model systems: Excitons in semiconductors and vanadium oxides.
We study many different aspects of single and many-body aspects of hydrogen atom physics with excitons. To first approximation, the mathematical equations are the same for excitons and hydrogen atoms but due to the vastly different energy scales, what happens in astrophysical conditions can be easily observed in the lab if we substitute real hydrogen atoms with excitons.
Excitons are also technically important and part of our effort also goes into understanding specifics of light emission in semiconductors, especially the role of disorder.
[Current collaborators: Sumi Bhuyan (PhD), Rupak Bhattacharya (PhD), Kingshuk Mukhuti (PhD), Basabendra Roy (MS), Bipul Pal (colleague). Past collaborators--Richarj Mondal (PhD 2015)]
Phase Transition Dynamics
Another, quite unrelated, problem we are currently studying is the dynamics of first order phase transitions. These have a very rich phenomenology. Through conceptually simple but nevertheless controlled and precise experiments, we are studying various aspects of supercooling and superheating, phase coexistence, metastability and coarsening, dynamic hysteresis, noise, latent heat,...
[Current collaborators---Tapas Bar (PhD), Satyabrata Raj (colleague); A. A. Anees (MS). Past collaborators--- K. S. Sujith (MS 2015), Arsalan Asfraf (MS 2014); Sujeet Choudhary (MS 2015)]
With my colleague Bipul Pal, I share a spectroscopy lab. The primary technique that I use is low temperature photoluminescence spectroscopy. Biupl's expertise is in time-resolved pump probe spectroscopy of semiconductors. I have been learning this technique from him and we have developed a versatile picosecond excitation-correlation photoluminescence set up around the femtosecond laser. We also do linear and non-linear absorption spectroscopies to study the electronic states and carrier dynamics, mostly in quantum wells and quantum dots. To get a flavour of what we do, you can have a look at this poster on Richarj's recent work. Currently Rupak and Kinsgshuk are also working on measuring photoluminescence in magnetic fields (10 T) by integrating a homemade fibre optics arrangement and sample insert with a commercial Physical Property Measuring System (PPMS).
We have also set up a small pulsed high magnetic field facility (75 kJ) to do transport measurements up to 35 tesla. My colleagues Pradip Khatua and Uday Kumar have been very involved in various instrumentation and data processing aspects of the project.
We have also do resistivity (4K-300K), photoconductivity (4K-300K), noise measurements (77K-300K), and differential thermal analysis [latent heat] (77K-300K) measurements.