Browsing by Author "Jyotirmoy Sau"

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Anomalous Hall effect from gapped nodal line in the Co2FeGe Heusler compound
(American Physical Society, 2021) Gaurav K. Shukla; Jyotirmoy Sau; Nisha Shahi; Anupam K. Singh; Manoranjan Kumar; Sanjay Singh
Full Heusler compounds with cobalt as a primary element show anomalous transport properties owing to the Weyl fermions and broken time-reversal symmetry. We present here the study of anomalous Hall effect (AHE) in the Co2FeGe Heusler compound. The experiment reveals anomalous Hall conductivity (AHC) ∼100 S/cm at room temperature with an intrinsic contribution of ∼78 S/cm. The analysis of anomalous Hall resistivity suggests the scattering independent intrinsic mechanism dominates the overall behavior of anomalous Hall resistivity. The first principles calculation reveals that the Berry curvature originated by a gapped nodal line near EF is the main source of AHE in the Co2FeGe Heusler compound. The theoretically calculated AHC is in agreement with the experiment. © 2021 American Physical Society.
Hydrostatic pressure-induced anomalous hall effect in Co2FeSi semimetal
(Institute of Physics, 2024) Jyotirmoy Sau; Debanand Sa; Manoranjan Kumar
The Weyl points and nodal line emerge in the momentum space due to symmetry protected state in topological semimetal materials and these materials hold significance due to their unusual anomalous transport properties. In this manuscript, we study the topological properties of the electronic band structure of a half-metallic ferromagnet Co2FeSi employing the ab-initio density functional theory method and show that it is a strongly correlated material. The experimentally observed magnetic properties can be explained in terms of the Slater-Pauling (SP) rule and our calculations are consistent with it. We also investigate the band topology of Co2FeSi and find that there are three topological nodal lines at 380 meV above Fermi Energy (E F ). The degeneracy of these nodal lines is perturbed upon introducing spin-orbit coupling with magnetization along [001] direction. However, some points still preserve degeneracy and are identified as Weyl points, each associated with a specific Chern number. At the ambient pressure, the AHC properties of this material have only extrinsic contribution which is consistent with the experimental results. To make the AHC intrinsic, we tune the position of the nodal line close to the Fermi energy by applying the hydrostatic pressure up to 26 GPa. We also discuss crystal symmetries and their relation with nodal lines and Weyl points. © 2024 IOP Publishing Ltd.