Our research is primarily based on aberration corrected transmission electron microscopy and high resolution electron energy loss spectroscopy (HREELS). Besides general advanced characterization of materials, we are involved in quantitative HRTEM imaging, developing techniques for nano and atomic length scale probing of electronic structure of materials. We work in a FEI TITAN aberration corrected microscope, and also perform first principle based calculation using WIEN 2k.
We are also involved with basic aspects of epitaxial thin film growth of wide band gap semiconductors, 2D materials and their heterostructures in a PLD.
Development of quantitative electron magnetic circular dichroism techniques (EMCD) at nano scale in an aberration corrected transmission electron microscope. The work also involves development of a phenomenological model to extract magnetic moments quantitatively. The technique and method developed can extract element specific nano scale magnetic moments both spin and orbital moments in magnetic materials.
B Loukya, DS Negi, K Dileep, N Pachauri, A Gupta, R Datta, Physical Review B 91 (13), 134412, 2015.
A soft experimental technique was developed part of this work which can give information at one atomic plane resolution. The work extracted magnetic order differences between the core and surface of magnetic nanocrystals of CuCr2S4. Surface spin canting geometry has also been revealed in CoFe2O4 and Fe3O4 nanocrystals. by the same technique with better information compared to a recently developed spin polarized neutron technique.
D.S. Negi, H Sharona, U Bhat, S Palchoudhury, A Gupta, R. Datta, Physical Review B 95, 174444, 2017
DS Negi, B Loukya, K Ramasamy, A Gupta, R Datta, Applied Physics Letters 106 (18), 182402, 2015
State of the art advanced aberration corrected HRTEM and atomic resolution holography (double biprism) techniques have been utilized to count both Zn and O atoms along high symmetry crystal orientation of ZnO lattice from the image. It will be extended further to develop the methods and expand the scope of the techniques in materials science.
U Bhat, R Datta, Journal of Applied Physics 125 (15), 154902, 2019
The epitaxial growth of 2D material of MoS2, WS2, ReS2 and their hetero structures with BN have been demonstrated by PLD technique. Control over layer number and unique optical property in the heterostructure system are obtained. A strong emission at 2.3 eV is obtained due to coupled transition between BN valence band to MoS2/WS2/ReS2 conduction band.
Rajib Sahu, Dhanya Radhakrishnan, Badri Vishal, Devendra Singh Negi, Anomitra Sil, Chandrabhas Narayana, Ranjan Datta, Journal of Crystal Growth 470, 51-57, 2017
U Bhat, R Singh, B Vishal, A Sharma, H Sharona, R Sahu, R Datta, phys. status solidi B, 1700691, 2018
Relative structural stability (1T, 1Td, and 2H) and atomic organizations in ReS2-MoS2, and ReS2-WS2 alloy system have been elucidated by advanced HRTEM imaging technique and density functional theory based calculation.
H Sharona, B Vishal, U Bhat, A Paul, A Mukherjee, SC Sarma, SC Peter, R Datta, Journal of Applied Physics 126 (22), 224302, 2019.
R Sahu, U Bhat, NM Batra, H Sharona, B Vishal, S Sarkar, S Assa Aravindh, SC Peter, Iman S Roqan, PMFJ Costa, Ranjan Datta, Journal of Applied Physics 121 (10), 105101, 2017
This was an accidental discovery of stabilizing metastable wurtzite BN during thin film growth of BN in a PLD. The phase got stabilized under unusual low pressure and temperature condition which otherwise would require explosive temperature and pressure condition to stabilize the phase.
B Vishal, R Singh, A Chaturvedi, A Sharma, MB Sreedhara, R Sahu, Usha Bhat, Upadrasta Ramamurty, Ranjan Datta , Superlattices and Microstructures 115, 197-203, 2018
There are numerous other contributions in general characterizations in materials science e.g., dark diffused contrast in CoO and NiCo2O4 spinel thin films.
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