Research Interests
Quantum Transport and Theory
1) Transport, electronic and optical properties in Topological materials
2) DFT based exploration of new 2D, magnetic and topological materials
3) Collective density (plasmons) and spin excitations in various systems
4) Nanoscale device modelling
While these define the current broad interests of the group, we are always open to working on other interesting problems!
1) Transport, electronic and optical properties in topological materials
Analytical modelling of electrical transport and optical properties of materials using the effective low energy Hamiltonian, is a core strength of of our group. Currently, we are focussing this expertise to explore the electronic transport including magneto-electric and magneto-thermal transport, in topological materials such as Dirac and Weyl Semimetals of different kind, nodal line semimetals, topological insulators, etc.
To give an example:
One of the simplest approach for exploring the magneto-thermal and magneto-electric transport properties is to use the Berry-curvature connected Boltzman transport formalism. Most of the topological phases of materials (including those hosting relativistic quasiparticles), have a finite Berry-curvature in the momentum space. A finite Berry curvature, effectively acts as a magnetic field in the momentum space. For transport calculations, it modifies three things: 1) The equation of motion of the carriers, 2) the phase space volume, and 3) the non-equilibrium distribution function generated by an external perturbation in a material (either an electric field, or a temperature gradient). See attached Figure. 
2) DFT based exploration of new 2D, Dirac, and topological materials
This is a relatively new research area being explored by us (since 2016).
While there have been several theoretical prediction along with experimental verification for various Dirac and Weyl semimetal candidates, the field is still in its infancy, particularly with regards to realistic predictions of Dirac nodal line semimetals, Dirac star-fruit nodal-line semimetals, Dirac hourglass nodal line semimetals etc. We plan to explore new materials with relativistic quasi-particles using ab-initio density-functional theory. The starting point is to explore materials with known symmetries using density-functional theory, followed by a systematic symmetry analysis, and very fine band-structure calculations using the Wannier projections of the DFT based band-structure. Currently, we are focussed on nodal-line semimetals with exotic nodal hoops, and hourglass nodal line Dirac semi-metals and hourglass Dirac points, weak topological insulators, topological superconductors, etc.
For an example of the kind of work involved, see our recent PRB: Spin-orbit coupling driven crossover from a starfruitlike nodal semimetal to Dirac and Weyl semimetal state in CaAuAs.
3) Collective density (Plasmons) and spin excitations
This is an area I picked up during my postdoctoral study, learning from Marco, Rosario and Giovanni. I have been working in this field since 2012.
In the last few years, we have been systematically investigating collective excitations in Dirac and Weyl semimetals, among other materials hosting relativistic quasi-particles. These are generally based on the calculation of the current-current, and the density-density response function, respectively and we have a good expertise in these calculations. Currently we are exploring the impact of the tilt of Dirac and Weyl nodes, on their plasmonic properties.
4) Nanoscale Device Modelling
All of our work in this area is in collaboration with Prof. Yogesh Singh Chauhan, and we have been working together on this since 2012.
Here we do all three aspects of Device modelling: 1) Ab-initio based prediction of material properties, 2) Physics based modelling of nanoscale futuristic devices, as well as 3) Compact modelling (no loop, no integration!) of nanoscale devices -- to be used for large scale process simulations.
In addition to the above mentioned areas of current interest in our group. We are also interested in other problems related to condensed matter physics as well. Some of these are
-- Spintronics in semiconductors and other spin-orbit coupled systems, and hybrid semiconductor hetero-structures.
-- Physical properties of Graphene and other 2D materials.
-- Transport in low-dimensional quantum systems: Luttinger liquids, quantum Hall edge states.
Spintronics and transport in semiconductor-superconductor hybrid structure
The phenomena related to spin dynamics, spin-transport is very useful for spintronics in hybrid structures and has lots of potential applications. We are very interested in the physics of spintronic devices -- even though we are yet to publish any research paper in this field.
Graphene, other 2D materials, and topological insulators
The filed of 2D materials, along with that of topological insulators, is very interesting from a basic physics viewpoint and it also offer immense potential for practical applications. Our focus is on understanding the physics of these systems, emerging from experiments, using quantum mechanical calculations. Additionally, we are also interested in ideas related to novel transport phenomena and device applications in these systems.
Luttinger liquids, edge state physics in Quantum Hall systems, and transport in quasi-one dimensional systems
Most of my Ph.D. research was focussed on this research area in collaboration with Diptiman Sen, Sumati Rao and Sourin Das. Thus we are generally interested in studying various forms of Hall effects ( anomalous Hall effect, spin Hall effect, anomalous spin Hall effect etc.) in various semiconductor systems, and the related physics.