Browsing by Author "S. Bhattacharjee"

Now showing 1 - 3 of 3

Role of chemical disorder in tuning the Weyl points in vanadium doped Co2TiSn
(American Physical Society, 2021) Payal Chaudhary; Krishna Kant Dubey; Gaurav K. Shukla; Sanjay Singh; Surasree Sadhukhan; Sudipta Kanungo; Ajit K. Jena; S.-C. Lee; S. Bhattacharjee; Jan Minár; Sunil Wilfred D'Souza
The lack of time-reversal symmetry and Weyl fermions give exotic transport properties to Co-based Heusler alloys. In the present study, we have investigated the role of chemical disorder on the variation of Weyl points in Co2Ti1-xVxSn magnetic Weyl semimetal candidate. We employ the first principle approach to track the evolution of the nodal lines responsible for the appearance of Weyl node in Co2TiSn as a function of V substitution in place of Ti. By increasing the V concentration in place of Ti, the nodal line moves toward Fermi level and remains at Fermi level around the middle composition. Further increase of the V content, leads shifting of nodal line away from Fermi level. Density of state calculation shows half-metallic behavior for the entire range of composition. The magnetic moment on each Co atom as a function of V concentration increases linearly up to x=0.4, and after that, it starts decreasing. We also investigated the evolution of the Weyl nodes and Fermi arcs with chemical doping. The first-principles calculations reveal that via replacing almost half of the Ti with V, the intrinsic anomalous Hall conductivity increased twice as compared to the undoped composition. Our results indicate that the composition close to the 50% V doped Co2TiSn will be an ideal composition for the experimental investigation of Weyl physics. © 2021 American Physical Society.
The rectangular dielectric waveguide revisited
(1991) V.J. Menon; S. Bhattacharjee; K.K. Dey
The problem of the rectangular, step-index, dielectric waveguide is re-examined within the mode-matching framework by fully incorporating symmetry requirements but neglecting the effect of the corners. This leads to a set of neat-looking eigenvalue conditions in which the adjacent edges of the rectangle get coupled, and the agreement with exact computer-based results improves dramatically. © 1991.
Westiellopsis tiwarii sp. nov., a New Cyanobacterium from North-East India Soils
(Pleiades Publishing, 2024) M. Parmar; T.P. Jaiswal; S. Bhattacharjee; S.S. Singh; A.K. Mishra
Abstract: In modern times, cyanobacterial identification, characterization, and classification have adopted a pragmatic polyphasic approach assigning equal weight to the ecological, morphological, physiological, and molecular parameters. The paucity of data on cyanobacterial diversity across unexplored regions resulted in poor taxonomic characterization of cyanobacteria. Hence, the poorly explored North-Eastern lower Himalayan region of India was targeted and a true-branched soil inhabiting cyanobacterial strain KFS2 was isolated. Along with habitat analysis, morphological and 16S-rRNA gene-based molecular characterization of the isolated strain have been performed. The complex cellular morphology, uni-seriate to multi-seriate main filaments and branches, along with the 16S rRNA gene sequence-based phylogeny indicated affiliation of this strain with the genus Westiellopsis. Furthermore, the strain KFS2 showed unique morphological features such as the multi-seriate base of lateral branches, the presence of both intercalary and terminal heterocytes in the main filaments along with the intercalary position of heterocytes in the lateral branches, and was found to form a separate node with the Westiellopsis clade having strong bootstrap support in the 16S-rRNA gene-based phylogeny. Moreover, comparative analysis of folded secondary structures of D1-D1' and box-B in the 16S-23S ITS region of the strain also exhibited striking differences with other members of the genus. Considering all the unique morphological and molecular characteristics of the strain KFS2, it was suggested to represent a new species of the genus Westiellopsis, with the name Westiellopsis tiwarii being proposed in accordance with the International Code of Nomenclature of algae, fungi, and plants. © Pleiades Publishing, Ltd. 2024. ISSN 0026-2617, Microbiology, 2024, Vol. 93, No. 4, pp. 399–409. Pleiades Publishing, Ltd., 2024.