The group focuses on the growth, synthesis and characterization of quantum materials. These include two-dimensional (2D) systems such as vander Waal’s materials and heterostructures, topological insulators and strongly correlated oxide materials. The primary goal of the group is to develop an indigenous technology towards the realization of quantum resistance metrology by exploiting the integer quantum Hall effect (IQHE) for which the current focus is on epitaxial graphene, oxide heterostructures and topological insulator.  Experiments are corroborated using the first principles of density functional theory-based electronic structure calculations.

The group also carries out high precision QHE measurements with accuracy of 80 ppb or better. A 1 kOhm standard is directly measured against the GaAs/AlGaAs QHE and subsequently resistances in the range 1 Ohm to 1 MOhm are measured with very high accuracy. The CMC of the group for 1 kOhm measurement against QHE (U_c (k=2) = 80ppb) has been peer reviewed twice and it is at the BIPM website.

The group has 05 Scientists and 13 Ph.D students working on the various aspects of quantum materials, which includes (i) growth and synthesis using PLD, sputtering, etc  (ii) Materials characterization of structure, electronic, magnetic, optical and transport properties, and (iii) Theoretical and computational studies.

• Growth and optimization of epitaxial graphene for indigenous development of graphene-based Quantum Hall Resistance Standard
• Realization of quasi-2DEG in oxide heterostructures with focus on enhancing the carrier mobility at the hetero-interface.
• Growth and characterization of topological insulator (TI) thin films, laser MBE epitaxial III-nitrides and two-dimensional (2D) materials
• Band gap engineering in Two-dimensional materials and their interfaces through band-width  and band-filling control
• Electronic structure study of surfaces and interfaces using photoemission spectroscopy
• Defect engineering and metal-insulator transition in oxide surfaces and interfaces
• Multi-scale materials modeling using ab-initio electronic structure calculations

• High precision magnetotransport measurement and resistance ratio measurement system used in quantum resistance (QHR) metrology
  Typical specifications of the GaAs/AlGaAs based QHE devices used at NPL Device: GaAs-Al_xGa_1-xAs (x=0.3), GaAs (1.5eV) is lightly p-doped, AlGaAs (2.2eV) is n-doped, ~ 10-20 T^-1, n ~ 3-6 x 10¹⁵ m^-2, B (i=2)~ 7-9 T.
  
  

  Contact schematic (right) and actual device on TO8 holder with contacts

Longitudinal and transverse (Hall) resistance of a GaAs-Al_xGa_1-xAs (x=0.3) device measured at 1.3 K

• Growth system for Graphene Epitaxy (GrapE): An indigenously developed system for growth of epitaxial graphene on SiC

• Pulsed Laser Deposition (PLD) system with RHEED for the growth of all oxide 2DEG heterointerfaces
  
  
• Three source UHV-magnetron sputtering systems for the growth of intermetallic thin film superlattices/heterostructures (like TIs) for QAHE and SHE
  
  
• Two HV-magnetron sputtering systems for the growth of all oxide FM/AFM, Superconductor/FM heterostructures, and topological insulator thin films/ heterostructures
  
  
• Temperature dependent photoconductivity measurement
  
  
• 3 Zone tube furnace for 2D materials growth
• Thermal evaporation
• Wire bonder

• Signature of weak-antilocalization in sputtered topological insulator Bi2Se3 thin films with varying thickness,  S. Gautam, V. Aggarwal, B. Singh, V.P.S. Awana, R. Ganesan, S. S. Kushvaha, Scientific Reports  12,9770 (2022).
• A Comparative Study of Superconductivity and Thermally Activated Flux Flow of YBa₂Cu₃O_7-δ and YBa₂Cu₃O_7-δ/La_1-x-yPr_xCa_yMnO₃ Bilayers; S Kumari, M Anas, DS Raghav, S Chauhan, PK Siwach, VK Malik, H K Singh, Journal of Superconductivity and Novel Magnetism 35 (11), 3225-3240 (2022)
• Investigation of RF sputtered, n-Bi2Se3 heterojunction on p-Si for enhanced NIR optoelectronic applications, Gautam, Sudhanshu Gautam, G. K. Maurya, K. Kandpal, Bheem Singh, R. Ganesan, S. S. Kushvaha, P. Kumar, Solar Energy Materials and Solar Cells 248, 112028 (2022).
• Probing phase separation in Nd_{1- x}Sr_xMnO₃ (x≈ 0.4, 0.5) polycrystals through temperature dependent magnetic and Raman spectroscopy studies, A Bhoriya, DS Raghav, N Bura, D Yadav, J Singh, HK Singh, ND Sharma, Journal of Alloys and Compounds 894, 162424 (2022)
• Charge transfer induced symmetry breaking in GaN/Bi2Se3 topological heterostructure device, F. Ahmad, R. Kumar, S.S. Kushvaha, M. Kumar, P. Kumar, npj 2D Materials and Applications 6, 12 (2022).
• Automation of Demonstrational Model of 1 g Kibble Balance Using LabVIEW at CSIR-NPL; B Ehetesham, T John, HK Singh, N Singh, Indian Journal of Pure & Applied Physics (IJPAP) 60 (1), 29-37 (2022)
• Book entitled “Types of Photodetectors and their applications”, Editors: S.S. Kushvaha and V.N. Singh, Page: 290 (8 chapters) Nova Science Publisher, US (2022)
• Anomalous conducting heterointerface of non-stoichiometric Ca_xTa_yO_3+δ/SrTiO₃^, Sumit Kumar, D S Rana, Biswarup Satpati, Sunil Ojha, Bhasker Gahtori, J. J. Pulikkotil, Anjana Dogra; J. Alloys and Compounds  876, 160064 (2021)
• Propensity of spin fluctuations in disordered NiCoCr alloys: A first principles study J J Pulikkotil, J. Alloys and Compounds 864, 158817 (2021)
• Interface induced reemergent insulator-metal transitions in ferromagnetic/ antiferromagnetic manganite superlattices, S Chauhan, S Kumari, P K Siwach, K K Maurya, V Malik, H K Singh, Physica E: Low-dimensional Systems and Nanostructures 128, 114573 (2021)
• Comparison of Pseudorandom Number Generators and Their Application for Uncertainty Estimation Using Monte Carlo Simulation, Karan Malik, Jiji Pulikkotil, Anjali Sharma, Mapan 36, p 481–496 (2021)
• Controlled epitaxial growth of GaN nanostructures on sapphire (11-20) using laser molecular beam epitaxy for photodetector applications, V. Aggarwal, C. Ramesh, P. Tyagi, S. Gautam, A. Sharma, S. Husale, M. S. Kumar, S. S. Kushvaha,Mater. Sci. Semicond. Processing  125,105631 (2021).
• Magnetic-order induced effects in nanocrystallineNiO probed by Raman spectroscopy
• N Bala, HK Singh, S Verma, S Rath, Physical Review B 102 (2), 024423 (2020)
• Emergence of quasi-two-dimensional electron gas at the interface of LaAlO₃/Sr₂AlNbO₆(001) heterostructures, JJ Pulikkotil J. Applied Physics 127, 225303 (2020)
• A spin–orbit coupling-induced two-dimensional electron gas in BiAlO 3/SrTiO 3 heterostructures, JJ Pulikkotil, Phys. Chem. Chem. Phys. 22, 3122-3127 (2020)
• Flexible perylenediimide/GaN organic-inorganic hybrid system with exciting optical and interfacial properties,  R. Kumar,S. S. Kushvaha, M. Kumar, M. S. Kumar, G. Gupta, K. Kandpal, P. Kumar,Scientific Reports  10,10480 (2020).
• LaScO₃/SrTiO₃: A conducting polar heterointerface of two 3d band insulating perovskites, Sumit Kumar, Jyoti Kaswan, Biswarup Satpati, A. K. Shukla, Bhasker Gahtori, J. J. Pulikkotil, Anjana Dogra ; Appl. Phys. Lett. 116, 051603 (2020)
• Journey of Kilogram from Physical Constant to Universal Physical Constant (h) via Artefact: A Brief Review; B Ehtesham, T John, S Yadav, HK Singh, G Mandal, N Singh, Mapan 35 (4), 585-593 (2020)
• Effect of spin-orbit interaction on the vortex dynamics in LaAlO₃/SrTiO₃ interfaces near the superconducting transition, Gopi Nath Daptary, Hemanta Kumar Kundu, Pramod Kumar, Anjana Dogra, Narayan Mohanta, A. Taraphder, and Aveek Bid; Phys. Rev. B. 100, 125117 (2019)
• Coexistence of quasi-two dimensional electron and hole gas in a single tier Ca₅TaO₃/SrTiO₃oxide heterostructure, J J Pulikkotil, APL Materials 7, 071108 (2019)
• Magnetic and Magnetotransport Characteristics of Cr-Substituted Ni₅₅Mn₃₄Sn₁₁ Thin Films Grown by Magnetron Sputtering; B Borgohain, PK Siwach, N Singh, K V R Rao, H K Singh; Journal of Superconductivity and Novel Magnetism 32 (10), 3295-3304 (2019)
• Martensitic ferromagnetism and spin glass behaviour in Ni₄₇Mn₃₆Cr₄Sn₁₃ ribbons, B Borgohain, P K Siwach, N Singh, V P S Awana, H K Singh; Intermetallics 111, 106492 (2019)
• Bilateral comparison of 1 Ω and 10 kΩ standards (ongoing BIPM key comparisons BIPM. EM-K13. a and 13. b) between the NPLI (India) and the BIPM, N Fletcher, R Goebel, M Saleem, HK Singh, MA Ansari, U Kiran, A K Saxena, Metrologia 56 (1A), 01007 (2019)
• Nonlinear I-V characteristics of two-dimensional superconductors: Berezinskii-Kosterlitz-Thouless physics versus inhomogeneity, G. Venditti, J. Biscaras, S. Hurand, N. Bergeal, J. Lesueur, A. Dogra, R. C. Budhani, Mintu Mondal, John Jesudasan, Pratap Raychaudhuri, S. Caprara, and L. Benfatt; Phys. Rev. B. 100, 064506 (2019)
• Effect of multiband transport on charge carrier density fluctuations at the LaAlO ₃/SrTiO ₃ interface, Gopi Nath Daptary, Pramod Kumar, Anjana Dogra, Aveek Bid;  Phys. Rev. B. 98, 035433 (2018)
• Competition between electron pairing and phase coherence in superconducting interfaces,  G. Singh, A. Jouan, L Benfatto, F. Couedo, P Kumar, A. Dogra, R. Budhani, S. Caprara, M. Grilli, E. Lesne, A  Barthélémy, M. Bibes, C. Feuillet-Palma, J. Lesueur, and N. Bergeal, Nature Communications 9: 407 (2018).

• 1 kOhm measurement against QHE (U_c(k=2) = 80ppb)

Dr. Jiji T J Pulikkotil
Chief Scientist
Email: jiji@nplindia.org
Ph: 011 45609364

Dr. Anjana Dogra
Sr. Principal Scientist, Head
Email: anjanad@nplindia.org
Ph: 011 45721097

Dr. Sunil Singh Kushvaha
Principal Scientist, Deputy Head
Email: kushvahas@nplindia.org
Ph: 011 45609329

Dr. Ajay Kumar Shukla
Principal Scientist
Email: shuklaak@nplindia.org
Ph: 011 45609329

Dr. P K Siwach
Principal Scientist
E-mail: siwachpk@nplindia.org
Ph: 011 45608604

Dr. Anjana Dogra
Sr. Principal Scientist, Head
Quantum Resistance Metrology & 2D Physics
Electrical & Electronic Metrology Division
Email: anjanad@nplindia.org
Ph: 011 45721097