Research

Our research is centered around probing phonon dynamics and coupling of phonons with other quasi-particles excitations in diverse range of condensed matter systems, with particular focus on Quantum Materials (QM) and 2D materials.

Correlated electronic systems which are subset of QM are host to a vast variety of quasi-particle excitations and intricate coupling between them gives rise to very rich ground states such as superconductivity, multiferroicity, Mott insulator and topologically active phases such as Quantum Spin Liquid (QSL) state. Topologically active phases result in very rich states of matter such as QSL, Topological Insulator, Weyl semimetal, Axion insulators to name a few, and these systems have potential for numerous applications as they are conjectured to be suitable for quantum computing. Probing these complex systems with competing multiple degrees of freedom is very challenging as well as intriguing. Our studies reveal an exotic quasi-particle excitation namely spin fractionalization evincing the signature of a QSL state in a three-dimensional solid. We are also planning to probe these exciting quantum materials under high pressure as these materials are expected to deliver surprises under extreme perturbation. 

Our focus on 2D materials is to explore the challenging basic physics issues such as coupling between different quasi-particle excitations and their role in controlling the electronic dynamics.

What is a correlated system?

The simplest and first example, where QM is at play, that we encountered is the particle in box problem during our undergrad. Now if add one more particle to this box and ask the same question - what happen to the dynamics? It is still a simple problem to work with. Let’s top it up with interactions, switch on the interactions between these particles, and see what happens – for two particles it is still manageable to work with pen and paper. But in any real system, the number of particles is really huge, of the order of Avogadro’s number - 10²³. The sheer magnitude of this number is startling and now switch on the interactions between them and that too strong interaction, this is what’s a strongly correlated system is. 

One of our aims is to look at the dynamics of such strongly correlated system and probe it using inelastic light scattering probe, in particular Raman scattering as a function of different external perturbations. What exactly happens is a photon, with given energy and momentum, goes in and talks to the different quasi-particles of the system under probe and comes out with some information. One needs to understand what exactly did they, photon and quasi-particles, whisper among themslep and how much information the quasi-partlces have revealved to the outgoing photons.