I am Ritajit Kundu, currently a research scholar at the Indian Institute of Technology Kanpur, doing my research work in theoretical condensed matter physics. I am financially supported by the Ministry of Human Resource Development, Govt. of India under the Prime Minister’s Research Fellows scheme. I can be contacted at ritajit@iitk.ac.in.

My research focuses on the aspects of many-body physics and topology of condensed matter systems, especially in mesoscopic physics of quantum heterostructure systems. Heterostructures are electronic systems made up of several components that are only loosely coupled. When such systems are in close proximity, interactions between subsystems can drive the system into novel phases that the subsystems do not possess. Using the analytical and numerical tools of quantum many-body field theory, my current goal is to understand these distinct phases of complex systems and to identify their potential applications in future quantum technologies.

## Supervisor

I am being supervised by Prof. Arijit Kundu and Prof. Amit Dutta at IITK. Links to their web pages are given herein.

## Prof. Arijit Kundu

Assistant Professor

Department of Physics, IITK

## Prof. Amit Dutta

Professor

Department of physics, IITK

## Education

• B.Sc physics Scottish Church College Kolkata (2014-2017)
• M.Sc Physics Indian Institute of Technology Kanpur (2017-2019)
• PhD Physics Indian Institute of Technology Kanpur (2019-present)

## Teaching duties

Apart from research work, I am also involved in some teaching duties. This consists in assisting instructors in the courses at IITK or teaching in other institutions.

I am giving weekly tutorials on physics problem-solving to class XII students at Kendriya Vidyalaya, IIT Kanpur Campus, mainly focusing on the National entrance examinations.

I was teaching assistant in the following courses at IIT Kanpur

• PHY441 Electronics During 2019 odd semester at IITK.
• PHY543 Condensed Matter Physics during 2020 odd semester at IITK.
• PHY607 Quantum Many Body Physics at IITK during 2020 even semester.
• PHY101 UG lab, during 2021 odd semester at IITK.

I also have a YouTube channel where I post physics-related videos on a regular basis.

## Awards

• Academic excellence award at IITK ( 2018 )
• Prime Minister’s Research Fellow ( May 2019 - present )

## Confrerences

• In the APS March Meeting 2022, I presented our work “Broken symmetry and competing orders in Weyl semimetal interfaces with Fermi arc states

Abstract:

Weyl semimetal (WSM) slabs hosting Fermi arc surface states in proximity can give rise to broken symmetry phases, due to emergent excitonic order, in presence of Coulomb interactions. In such a phase, correlations between low-energy interlayer fermions become non-zero even without any tunnelling processes. The recently found WSM Co$_3$Sn$_2$S$_2$ and the proposed WSM 4-2 Spinel compound, which respectively hosts two and three Fermi arcs in the surface Brillouin zone, provide platforms to examine the effects of multiple Fermi arcs in such phases. We find that such a system hosts different excitonic orders, such as zero momentum exciton modes as well as finite momentum exciton modes and charge-density wave orders. These orders break a number of U(1) symmetries, whereas charge density wave orders also break translation symmetry. Broken U(1)-symmetries give rise to Goldstone modes with interesting transport signatures and potential applications in quantum technologies.

Session #: Y59

Title: Dirac and Weyl Semimetals: Theory I

Day: Friday

Date: 3/18/2022

Ritajit Kundu, Herb Fertig, Arijit Kundu

## Publications

• Kundu, R., Fertig, H.A, Kundu, A., 2022. Broken symmetry and competing orders in Weyl semimetal interfaces, arXiv preprint arXiv:2205.13254

• Mukherjee, R., Kundu, R., Singh, A. and Kundu, A., 2021. Schwinger-Boson mean-field study of spin-$1/2$ $J_1$-$J_2$-$J_{\chi}$ model in honeycomb lattice: thermal Hall signature. arXiv preprint arXiv:2108.08801

• Mohapatra, S., Kundu, R., Dubey, A., Dutta, D. and Singh, A., 2021. Role of orbital off-diagonal spin and charge condensates in a three orbital model for Ca$_2$RuO$_4$–Coulomb renormalized spin-orbit coupling, orbital moment, and tunable magnetic order. Journal of Magnetism and Magnetic Materials, 537, p.168172. 10.1016/j.jmmm.2021.168172