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Birabar Ranjit Kumar Nanda
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Birabar Ranjit Kumar Nanda
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Birabar Ranjit Kumar Nanda
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Nanda, Birabar Ranjit Kumar
Nanda, B. Ranjit K.
Nanda, Birabar R.K.
Nanda, B. R.K.
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3 results
Now showing 1 - 3 of 3
- PublicationOrbital driven impurity spin effect on the magnetic order of quasi-3D cupric oxide(13-03-2017)
;Ganga, B. G.; Density functional calculations are performed to study the magnetic order of the severely distorted square planar cupric oxide (CuO) and local spin disorder in it in the presence of the transition metal impurities M (=Cr, Mn, Fe, Co and Ni). The distortion in the crystal structure, arisen to reduce the band energy by minimizing the covalent interaction, creates two crisscrossing zigzag spin-1/2 chains. From the spin dimer analysis we find that while the spin chain along (1 0 1) has strong Heisenberg type antiferromagnetic coupling (J ∼ 127 meV), along it exhibits weak, but robust, ferromagnetic coupling (J ∼ 9 meV) mediated by reminiscent p-d covalent interactions. The impurity effect on the magnetic ordering is independent of M and purely orbital driven. If the given spin-state of M is such that the dx2-y2 orbital is spin-polarized, then the original long-range ordering is maintained. However, if dx2-y2 orbital is unoccupied, the absence of corresponding covalent interaction breaks the weak ferromagnetic coupling and a spin-flip takes place at the impurity site leading to breakdown of the long range magnetic ordering. - PublicationDensity Functional Theory Studies of Si2BN Nanosheets as Anode Materials for Magnesium-Ion Batteries(25-09-2020)
;Panigrahi, Puspamitra ;Mishra, Shashi B. ;Hussain, Tanveer; Ahuja, RajeevThe unique structural characteristics make the 2D materials potential candidates for designing negative electrodes for rechargeable energy storage devices. Here, by employing density functional theory (DFT) calculations, we study the precise viability of using Si2BN, a graphene-like 2D material, as a high-capacity anode material for Mg-ion battery (MIB) application. The favorable Mg-adsorption sites with maximum possible coverage effect are explored in detail. It is found that the Si2BN sheet can be adsorbed to a configuration of Mg8Si16B8N8, which proposes a theoretical capacity of 647.896 mA h g-1 for divalent Mg2+-ion battery applications. The average open-circuit voltage of 0.6-0.7 V and intercalation migration energy barrier in the range of 0.08-0.35 eV make Si2BN one of the most promising anode materials for MIB applications. The porous Si2BN with high structural stability and metallic electronic structures along with the low Mg2+-ion migration barrier energies predict high electron and Mg-ion conductivity, ensuring fast charge/discharge cyclic performance. The above-mentioned findings validate that the Si2BN sheet can work as an excellent high-performance anode material for MIBs. - PublicationShifting of Fermi level and realization of topological insulating phase in the oxyfluoride BaBiO2F(22-03-2019)
;Khamari, BramhachariThe disadvantage of BaBiO3 of not being a topological insulator despite having symmetry protected Dirac state is overcome by shifting the Fermi level (EF) via fluorination. The DFT calculations reveal that the fluorination neither affects the spin-orbit coupling nor the parity of the states, but it acts as a perfect electron donor to shift the EF. We find that 33% fluorination is sufficient to shift the EF by ∼2 eV so that the invariant Dirac state lies on it to make BaBiO2F a topological insulator. The fluorinated cubic compound can be experimentally synthesized as the phonon studies predict dynamical stability above ∼500 K. Furthermore, the Dirac states are found to be invariant against the low-temperature phase lattice distortion which makes the structure monoclinic. The results carry practical significance as they open up the possibility of converting the family of superconducting oxides, ABiO3 (A = Na, K, Cs, Ba, Sr, Ca), to real topological insulator through appropriate fluorination.