Dr. Subhra Sen Gupta | Department of Physics

Profile

Dr. Subhra
Sen Gupta
Assistant Professor
Department of Physics
School of Natural Sciences (SNS)
A023-J, Shiv Nadar University
Gautam Buddha Nagar Uttar Pradesh
India
91-0120-7170100
Extn: 
391
Profile Summary 

I joined Shiv Nadar University, Delhi-NCR in December 2014, from the RIKEN Wako Institute, Japan, where I started after receiving the prestigious Foreign Postdoctoral Researcher (FPR) Fellowship of RIKEN. Prior to that, I was a Post-doctoral Research Fellow (with part-time appointment as Postdoctoral Teaching Fellow) in the renowned group of Prof. G. A. Sawatzky at the University of British Columbia, Vancouver, Canada, with a brief stint as a Visiting Research Associate in the Department of Condensed Matter Physics & Material Science, S.N. Bose National Centre for Basic Sciences, Kolkata, in between.

I did my M.S. and Ph.D. in the Department of Physics, Indian Institute of Science, Bangalore, under the Integrated Ph.D. program. I am a Theoretical Condensed Matter Physicist, specializing in the field of Strongly Correlated Electron Systems, where electron-electron interactions cannot be treated as a perturbation to its motion in the crystal potential, resulting in the breakdown of conventional band-structure description for such systems, at least in the rigourous sense. On one hand, this field helps us to better understand the exotic phenomena that can emerge out of strong, non-perturbative interactions between electrons in a narrow-band solid, like compounds of transition metals, rare-earths and actinides. On the other hand, a basic understanding of the physics of these materials helps to design “smart materials” with advanced and energy-efficient functionalities.

I have been working in this field for more than a decade, trying to model the ground state (low-energy) as well as the spectroscopic (high-energy) properties of correlated electron systems, under the mentorship of and in collaboration with leading international experts in the field. More specifically, my research interests lie in the Modeling of Electronic and Magnetic properties of Strongly Correlated Systems, X-ray Spectroscopies, Spin & Orbital Magnetism and Magneto-crystalline Anisotropy in Nano-structured materials, and development of New Computational Tools for Correlated Systems. Our work has been published in leading International Journals and is well-cited.

Educational Qualifications 
2007
Doctor of Philosophy (Ph.D.) [Specialization : Theoretical Condensed Matter Physics]
Indian Institute of Science (IISc), Bangalore, India (Integrated Ph.D. Program).
2000
M.S. (Physical Sciences).
Indian Institute of Science (IISc), Bangalore, India (Integrated Ph.D. Program).
1997
B.Sc. (Physics Hons.)
St. Xavier’s College, Kolkata, India (University of Calcutta).
Work Experience 
12/14Present
Assistant Professor,
Department of Physics, School of Natural Sciences, Shiv Nadar University, Delhi-NCR
I currently work here
01/13
12/14
RIKEN FPR (Foreign Postdoctoral Researcher) Fellow,
RIKEN (Computational Condensed Matter Physics Laboratory, ASI/CEMS),
Wako, Japan.
03/12
12/12
Visiting Research Associate, Department of Condensed Matter Physics and Material Science,
S.N. Bose National Centre for Basic Sciences,
Kolkata, India.
03/08
02/12
Post-doctoral Research (and Teaching) Fellow, Department of Physics & Astronomy,
University of British Columbia (UBC),
Vancouver, BC, Canada.
01/07
02/08
Postdoctoral Fellow, Department of Material Science,
S. N. Bose National Centre for Basic Sciences,
Kolkata, India.
Teaching & Research Interests: 

RESEARCH :

The research in our group can be broadly classified as Theoretical Condensed Matter Physics. More specifically, our research focuses on the field of  Strongly Correlated Electron Systems (Ground State as well as Spectroscopic properties)., where electron-electron interactions cannot be treated as a perturbation to its motion in the crystal potential, resulting in the breakdown of conventional band-structure description for such systems, at least in the rigourous sense.

On one hand, this field helps us to better understand emergent phenomena that can arise out of strong, non-perturbative interactions between electrons in narrow-band solids, like compounds of transition metals, rare-earths and actinides. The hallmark of this is seen in exotic phenomena like colossal magnetoresistance in the Manganites, high-temperature superconductivity in the Cuprates, spin-charge separation and charge fractionalization in low-dimensional correlated systems, and the Kondo effect, to name a few. In such phenomena one simply cannot think of each electron independently, but must take into account the collective behaviour of a macroscopically large number (~ Avogadro's Number) of electrons, all acting in unison. On the other hand, a basic understanding of the physics of these materials helps in designing “smart materials” with advanced and energy-efficient functionalities.

Since treating the full correlation problem for an infinite solid is an unsolvable problem, the challenge for theory is to continuously develop newer and more efficient analytical approximations and numerical techniques to better understand the properties of these “quantum materials”, as constantly emerging from experiments. We have been working in this field for more than a decade, trying to model the ground state (low-energy) as well as the spectroscopic (high-energy) properties of correlated electron systems, in collaboration with leading experts in the field, both in India and abroad. We are interested both in model problems as well as in complex real materials. Our research interests and efforts are traditionally directed towards the following broad areas :

  • Electronic and magnetic properties of strongly correlated electron systems : Including mixed-valent systems, systems with strong spin-orbit coupling (e.g., 4d and 5d transition metal oxides), systems exhibiting exotic spin-orbital and hidden order.
  • Modeling of high-energy X-ray spectroscopies : e.g. XAS, AES, XPS, NIXS, RIXS etc. in strongly correlated systems.
  • Spin/orbital magnetism and magneto-crystalline anisotropy in nano-structured materials : e.g., surfaces/thin-films/multilayers/nano-particles etc.
  • Development of new computational tools for correlated electron systems.

More recently, I have developed an interest in some newer reaearch areas and am already pursuing active research in some of them. These are listed below :

  • Calculation of High-energy Optical Conductivity in Strongly Correlated Electron Systems (related to my DST Project ECR/2016/002054).
  • Application of Random Matrix Theory (RMT) to Disordered Quantum Electronic and Spin Systems.
  • Investigation of Astrophysical Magnetism using the methods of Statistical Physics.
  • Topological Aspects in Condensed Matter Physics.
  • Integrability, Ergodicity and Quantum Chaos in Quantum Lattice Models.
     

TEACHING :

I love teaching and am open to teaching almost any Core course and designing new Electives. Since January 2015, I have taught the following courses at SNU :

  • PHY102 : Introduction to Physics II, Laboratory (Under-graduate Core). [Spring 2015]
  • PHY203 : Introduction to Mathematical Physics I (Under-graduate Core). [Monsoon 2017, 2018]
  • PHY304 : Condensed Matter Physics (Under-graduate Core). [Spring 2015, 2016 & 2021]
  • PHY305 : Quantum Mechanics I (Under-graduate Core). [Monsoon 2015-2020]
  • PHY306 : Quantum Mechanics II (Under-graduate Core). [Spring 2016-2022]
  • PHY417 : Topics in Quantum Many Body Theory  (Under-graduate Advanced Elective, Suitable for Post-Graduates too). [Spring 2017-2018, Monsoon 2019-2021]
  • PHY508Review of Quantum Mechanics (Post-graduate Core). [Monsoon 2015]
  • CCC 422 : Demystifying the Strange Quantum World for the Layman [Spring 2020 (2 batches), Monsoon 2021 (one batch), Spring 2022 (two batches)]
  • PHY301 : Classical Mechanics (Under-graduate Core). [Monsoon 2021, Monsoon 2022]
  • PHY101 : Introduction to Physics - 1 (Under-graduate Core, Service Course for Engineering). [Monsoon 2022]

DOCTORAL RESEARCH STUDENTS :

  • Debojyoti Kundu (About to Present Synopsis)
  • Irfan Nazir Mir (1st Year)
  • Firdous Haider (1st Year)

UNDERGRADUATE RESEARCH STUDENTS :

I. UNDERGRADUATE THESIS

2019-2020 [Graduated 2020]

  • Kartikeya Rambhatla (Grade : A-).

2018-2019 [Graduated 2019]

  • Vikas S. Bhat (Grade : A-, Pursuing Integrated Ph.D. at TIFR, Mumbai).
  • Ninaad Adhvaryu (Grade : A-, About to start Masters in Physics at University of Stuttgart, Germany.)

2017-2018 [Graduated 2018]

  • Siddharth Seetharaman (Grade : A, Pursuing Ph.D. at Ohio State University, USA).
  • Girish Kumar (Grade : A-, Pursuing Masters in Astrophysics at University of Amsterdam, The Netherlands).
  • Prakriti Kayastha (Grade : A-, Pursuing Ph.D. at TIFR, Hyderabad).

II. OPPORTUNITIES FOR UNDERGRADUATE RESEARCH (OUR)

2021-2022

  • Akshat Pandey

2022-2023

  • Arvind Vinod
Awards(Selected): 
2022

Invited Speaker and Session Chair at the International Conference “6th Young Investigators Meet on Quantum Condensed Matter Theory (YIMQCMT-2022)" organized by NISER, Bhubaneshwar, during October-November, 2022.

2022

Invited Speaker and Co-organizer of the the National Conference : “d-d Transitions : A Discussion Meeting on the Electronic Structure of Materials” held at Colva, Goa (August, 2022).

2021

Invited Speaker at the International Conference “5th Young Investigators Meet on Quantum Condensed Matter Theory (YIMQCMT-2021)" organized by NISER, Bhubaneshwar, during November, 2021.

2021

Invited Speaker at the International Conference “Interdisciplinary Topics in Advanced Materials (ITAM-2021)” organized jointly by IISc and JNCASR, Bangalore during July, 2021

2019

NORDITA Academic Visitor in the Astrophysics Group of Nordic Institute for Theoretical Physics (NORDITA), Stockholm, Sweden (June, 2019).

2016

Early Career Research Award, SERB (DST), India.

2012

Selected for the prestigious RIKEN Foreign Postdoctoral Researcher (FPR) Fellowship, RIKEN, Japan (about 20 candidates selected Internationally every year, including the fields of Physics, Chemistry, Biology, Medicine and Engineering)

2007

Spontaneously offered a Post-doctoral Position in the renowned Sawatzky Group, at the University of British Columbia, Vancouver, Canada, after receiving a exceptionally good Ph.D. Thesis Report from Prof. G. A. Sawatzky, a father figure in the field.

1997

Selected for the Integrated Ph.D. Fellowship/Program of the Indian Institute of Science, Bangalore, India. Followed by the IISc JRF and SRF Fellowships in 1999 and 2002.

1997

National Merit Scholar (1997) (Govt. of India) on the basis of B.Sc. (Hons.) results.

1994

National Merit Scholar (1994) (Govt. of India) on the basis of XII std. results (ranked 40th in the state).

Scholarly Activity

​SELECT JOURNAL PUBLICATIONS (AND SUBMITTED)

  • Signatures of spectral crossovers in the short- and long-range spectral correlations of a disordered spin-chain with Kramers degeneracy : Debojyoti Kundu, Santosh Kumar*, Subhra Sen Gupta* (Under Review in Phys. Rev. B, 2022).
  • Spectral Crossovers and Universality in Quantum Spin-chains Coupled to Random Fields : Debojyoti Kundu, Santosh Kumar*, Subhra Sen Gupta*, Phys. Rev. B 105, 014205 (2022).
  • RMT Spectral Distribution Crossovers in Random Spin Chains, Debojyoti Kundu, Santosh Kumar, Subhra Sen Gupta, Bulletin of the American Physical Society (2021).
  • Coexistence of Bound and Virtual-bound States in Shallow-core to Valence X-ray Spectroscopies : Subhra Sen Gupta*, J. A. Bradley, M. W. Haverkort, G. T. Seidler, A. Tanaka, and G. A. Sawatzky, Phys. Rev. B 84, 075134 (2011).
  • The Importance of Inter-site Coherences in the X-ray Absorption Spectra of Mixed-valent Systems : Subhra Sen Gupta*, Hiroki Wadati and G. A. Sawatzky, Europhysics Letters 93, 47008 (2011).
  • Probing electronic correlations in actinide materials using multipolar transitions : J. A. Bradley, Subhra Sen Gupta, G. T. Seidler, K. T. Moore, M. W. Haverkort, G. A. Sawatzky, S.D. Conradson, D. L. Clark, S. A. Kozimor, and K. S. Boland, Phys. Rev. B 81, 193104 (2010).
  • Supramolecular control of the magnetic anisotropy in two-dimensional high-spin Fe arrays at a metal interface : P. Gambardella, S. Stepanow, A. Dmitriev, J. Honolka, Frank de Groot, M. Lingenfelder, Subhra Sen Gupta, D. D. Sarma, P. Bencok, S. Stanescu, S. Clair, S. Pons, N. Lin, A. P. Seitsonen, H. Brune, J. V. Barth and K. Kern, Nature Materials (Letters) 8, 189 (2009).
  • Theory of the unusual doping and temperature dependence of photoemission spectra in manganites : Prabuddha Sanyal, Subhra Sen Gupta, Nandan Pakhira, H. R. Krishnamurthy, D. D. Sarma and T. V. Ramakrishnan, Europhysics Letters 82, 47010 (2008).
  • Spin-flop ordering from frustrated ferro- and antiferromagnetic interactions : A combined theoretical and experimental study of a Mn/Fe(100) monolayer : C. Grazioli, D. Alfe, S.R. Krishnakumar, Subhra Sen Gupta, M. Veronese, S. Turchini, N. Bonini, A. Dal Corso, D. D. Sarma, S. Baroni and C. Carbone, Phys. Rev. Lett. 95, 117201 (2005).
  • X-ray absorption spectroscopy of transition-metal doped oxide diluted magnetic semiconductors Zn1-xMxO : J. Okabayashi, K. Ono, M. Mizuguchi, M. Oshima, Subhra Sen Gupta, D. D. Sarma, T. Mizokawa, A. Fujimori, M. Yuri, C.T. Chen, T. Fukumura, M. Kawasaki and H. Koinuma, J. Appl. Phys. 95, 3573 (2004).
  • Synthesis and Characterization of Mn doped ZnO Nanocrystals : Ranjani Viswanatha, Sameer Sapra, Subhra Sen Gupta, B. Satpati, P. V. Satyam, B. N. Dev and D. D. Sarma, J. Phys. Chem. B 108, 6303 (2004).

MANUSCRIPTS IN PREPARATION

  • Next-nearest Neighbour Spacings Distribution and Long-range Spectral Statistics in a Variety of Correlated Spin Models - A Comparison with Random Matrix Theory :  Debojyoti Kundu, Santosh Kumar*, Subhra Sen Gupta* (In preparation, to be submitted to Phys. Rev. B).
  • Chaos and Multi-fractality in Quantum Spin Models : Debojyoti Kundu, Subhra Sen Gupta* (In preparation, to be submitted to Phys. Rev. B).
  • A Quantum Origin for Super-strong Magnetic Fields in some Magnetized White Dwarfs : Subhra Sen Gupta* and Dhrubaditya Mitra* (In preparation, to be submitted to Mon. Not. R. Astron. Soc.,).
  • Bond-polarizability induced concomitant Charge-Transfer to Mott-Hubbard crossover at the Spin-state transition in the Cobaltates, Subhra Sen Gupta* and G. A. Sawatzky (In preparation, to be submitted to Phys. Rev. Lett.,).

INVITED PRESENTATIONS

  • “Chaos and Multifractality in Quantum Spin Systems" at the National Conference : “Young Investigator’s Meet on Quantum Condensed Matter Theory (YIMQCMT - 2022)” held at NISER, Bhubaneshwar (November, 2022).
  • “Symmetry, Integrability and Chaos in Quantum Spin Systems" at the National Conference : “d-d Transitions : A Discussion Meeting on the Electronic Structure of Materials” held at Colva, Goa (August, 2022).
  • "Universal Behaviour of Multi-point Spectral Correlations across Spectral Crossovers in Stochastic Quantum Spin Chains" at the International Conference : “5th Young Investigators Meet on Quantum Condensed Matter Theory (YIMQCMT-2021)" organized by NISER, Bhubaneshwar (November, 2021).
  • "Spectral Crossovers and Universality in Quantum Spin-chains Coupled to Random Fields",  at the International Conference : Interdisciplinary Topics in Advanced Materials (ITAM-2021) organized jointly by IISc and JNCASR, Bangalore. (July, 2021).
  • "Bond-polarizability induced Charge-Transfer to Mott-Hubbard Crossover at the Spin-state Transition in Cobaltates", at the 7th Indian Statistical Physics Community Meeting (ISPCM-2020) held at ICTS, Bangalore (February, 2020).
  • "A Quantum Mechanism of Magnetism in White Dwarfs", at the 6th Indian Statistical Physics Community Meeting (ISPCM-2019) held at ICTS, Bangalore (February, 2019).
  • "Magnetism in Super-Condensed Phases of Matter" at the Young Investigators Meet in Quantum Condensed Matter Theory (YIMQCMT-2018) held at S.N. Bose Centre, Kolkata (November, 2018).
  • “Strong Hybridization Effects on the "Hubbard U" and "Hund's Rule" in Strongly Correlated Electron Systems” at the CMPU, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India. (June, 2015). 
  • “Strong Hybridization Effects on the Hubbard U and the Hund’s coupling in Strongly Correlated Electron Systems” in the Department of Physics, University of Tokyo, Japan. (November, 2014).
  • “Unusual role of Multipole Coulomb Interactions in determining Spin-orientation on Correlated Surfaces” at the 6th Indo-Japan Meeting on Physics and Design of Multi-functional Correlated Materials, held at the University of Tokyo, Japan. (March, 2014).
  • “Breakdown of the single-site approximation in core-level X-ray spectroscopies” at the Saha Institute of Nuclear Physics (SINP), Kolkata, India. (December, 2012).
  • “An introduction to Non-resonant Inelastic X-ray Scattering (NIXS) - a versatile tool to study the electronic structure of complex oxides” at the Indo-EU ATHENA-2012 Advanced School on Modeling Complex Oxides, held at S. N. Bose National Centre for Basic Sciences. (April, 2012).
  • “Coexistence of bound and virtual-bound states in shallow-core to valence x-ray spectroscopies” at the S. N. Bose National Centre for Basic Sciences. (January, 2011).
  • “Non-resonant Inelastic X-ray Scattering (NIXS) in the Actinides and the Rare-earths: Some Generalities” at the X-ray Scattering Workshop at Stanford Institute of Materials and Energy Sciences Department, SLAC National Accelerator Laboratory, Stanford University, Palo Alto, USA. (August, 2009). 

CONTRIBUTED PRESENTATIONS

  • "Variable-Range Spectral Correlations in 1D Correlated Quantum Spin-Chains", at the National conference on Quantum Condensed Matter (QMAT - 2021) organized by TIFR, Mumbai (Online mode, December, 2021). [Presented by Student, Debojyoti Kundu].
  • "Long-range Spectral Statistics in a Variety of Correlated Spin Models: A Comparison with Random Matrix Theory", at the 5th Young Investigators Meet on Quantum Condensed Matter Theory (YIMQCMT-2021) organized by NISER, Bhubaneshwar (Online mode, November, 2021). [Presented by Student, Debojyoti Kundu].
  • "RMT Spectral Distribution Crossovers in Random Spin Chains"  Oral Presentation at the APS March Meeting (Online Mode, March 2021).  [Presented by Student, Debojyoti Kundu].
  • "Short and Long-range Spectral Statistics in a Variety of Correlated Spin Models : A Comparison with Random Matrix Theory", at the 7th Indian Statistical Physics Community Meeting (ISPCM2020), held at ICTS, Bangalore (February 2020). [Presented by Student, Debojyoti Kundu].
  • "RMT Spectral Distribution Crossovers in Random Spin Systems", at the 6th Indian Statistical Physics Community Meeting (ISPCM2019), held at ICTS, Bangalore (February 2019). [Presented by Student, Debojyoti Kundu].
  • “Bond polarizability and large modification of the Hubbard U at the spin-state transition in Cobaltates” at the International Conference on Frontiers in Advanced Materials (FAM-2015), at the Indian Institute of Science, Bangalore, India. (June, 2015).
  • “Bond polarizability and large modification of the Hubbard U at the spin-state transition in Cobaltates” at the International Conference on Strongly Correlated Electron Systems (SCES-2014), at the Campus Saint Martin d’Hères, Grenoble, France. (July, 2014).
  • “Unusual role of Multipole Coulomb Interactions in determining Spin- orientation on Correlated Surfaces” at the Workshop on Oxide Electronics 20 (WOE20), at the National University of Singapore (NUS), Singapore. (September, 2013).
  • “The Importance of Inter-site Coherences in the X-ray Absorption Spectra of Mixed-valent Systems” at the MPI-UBC International School on Quantum Materials, held at the Max-Planck Institute for Solid State Research, Stuttgart, Germany. (October, 2010).
  • “High Momentum Transfer Shallow Core-to-valence Spectroscopy in the Actinides” at the APS March Meeting, held in Portland, Oregon, USA. (March, 2010)
  • “The Importance of High Momentum Transfer Shallow Core-to- valence Spectroscopy in the Actinides” at the PCAMM meeting, Simon Fraser University (SFU), Burnaby, Canada. (December, 2009).
  • “Non-resonant Inelastic X-ray Scattering (NIXS) in the Actinides and the Rare-earths: Some Generalities” at the Quantum Materials CIFAR Meeting, University of British Columbia (UBC), Vancouver, Canada. (May, 2009).
  • “Theoretical Investigation Of The Spin Reorientation Transition In Epitaxial Films Of NiO” at the International Conference on Magnetic Materials (ICMM), Saha Institute of Nuclear Physics (SINP), Kolkata, India. (December, 2007).
  • “Theory of the unusual doping and temperature dependent spectral weight transfer in the photoemission spectra of the manganites” at 1st Indo-Japan Conference, Indian Institute of Science (IISc), Bangalore, India. (February, 2006). 

PROJECTS/GRANTS

  • Early Career Research Award (ECRA) Grant of SERB (DST) [3-year budget of ~ 21 Lakhs], India, ECR/2016/002054, (2018-2021).
  • Research Grant of ¥ 1,000,000 per year (for 3 years) as a part of the RIKEN FPR Fellow Position at the RIKEN Wako Institute, Japan (2013-2016).