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Ghimire M.P.,Nepal Academy of Science and Technology | Ghimire M.P.,Japan International Center for Materials Nanoarchitectonics | Thapa R.K.,Mizoram University | Rai D.P.,Pachhunga University College | And 3 more authors.
Journal of Applied Physics | Year: 2015

First-principles density functional theory (DFT) is used to investigate the electronic and magnetic properties of Sr4Rh3O10, a member of the Ruddlesden-Popper series. Based on the DFT calculations taking into account the co-operative effect of Coulomb interaction (U) and spin-orbit couplings (SOC), Sr4Rh3O10 is found to be a half metallic ferromagnet (HMF) with total magnetic moment μtot=12μB per unit cell. The material has almost 100% spin-polarization at the Fermi level despite of sizable SOC. Replacement of Rh atom by the isovalent Co atom is considered. Upon full-replacement of Co, a low-spin to intermediate spin transition happens resulting in a HMF state with the total magnetic moment three-time larger (i.e., μtot=36μB per unit cell), compared to Sr4Rh3O10. We propose Sr4Rh3O10 and Sr4Co3O10 as candidates of half metals. © 2015 AIP Publishing LLC. Source


Shankar A.,Mizoram University | Rai D.P.,Pachhunga University College | Rai D.P.,Beijing Computational Science Research Center | Khenata R.,University of Mascara | Thapa R.K.,Mizoram University
Phase Transitions | Year: 2015

The elastic, electronic, magnetic and optical properties of filled skutterudite ROs4P12 (R = Sm, Eu and Gd) have been studied by first principles calculation. The full-potential linearized augmented plane wave method based on density functional theory was employed. For the exchange-correlation potential, local spin density approximation + Coulomb repulsion (LSDA + U) is used to treat the f-electrons more effectively. The numerical values of the elastic parameters are estimated in the framework of the Voigt-Reuss-Hill approximation. OsP-based filled skutterudite with localized 4f and 5d-electrons shows dense energy bands near Fermi energy originating from rare earth and Os atoms. The dense density of states near EF reveals that these compounds are suitable for thermoelectric application. Optical constants including dielectric function, optical reflectivity and refractive index are calculated for photon energy radiation up to 12 eV. The exchange-splitting of R-4f states were analyzed to explain the ferromagnetic behavior of ROs4P12. © 2015 Taylor and Francis. Source


Rai D.P.,Pachhunga University College | Shankar A.,Mizoram University | Sandeep,Mizoram University | Ghimire M.P.,Condensed Matter Physics Research Center | And 3 more authors.
RSC Advances | Year: 2015

A density functional theory (DFT) approach employing generalized gradient approximation (GGA) and the modified Becke Johnson (TB-mBJ) potential has been used to study the electronic and thermoelectric (TE) properties of ZrxHf1-x-yTayNiSn. The presence of an indirect band gap at EF in the parent compound predicts this material to be a small band gap insulator. The substitution of Ta atoms at the Hf site increases the density of states (DOS) at EF which facilitates charge carrier mobility. The influence of Ta content increases the Seebeck coefficient and electrical conductivity, and suppresses the thermal conductivity; as a result the figure of merit ZT is enhanced. We report an increment in ZT value of 36% over the undoped system. The theoretical data were compared with the experimental results. © The Royal Society of Chemistry. Source


Dahmane F.,Center University Of Tissemsilt | Dahmane F.,University Djilali Liabes | Mogulkoc Y.,Ankara University | Doumi B.,University Djilali Liabes | And 6 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2016

Using the first-principles density functional calculations, the structural, electronic and magnetic properties of the Fe2XAl (X=Cr, Mn, Ni) compounds in both the Hg2CuTi and Cu2MnAl-type structures were studied by the full-potential linearized augmented plane waves (FP-LAPW) method. The exchange and correlation potential is treated by the generalized-gradient approximation (GGA) where the results show that the Cu2MnAl-type structure is energetically more stable than the Hg2CuTi-type structure for the Fe2CrAl and Fe2MnAl compounds at the equilibrium volume. The full Heusler compounds Fe2XAl (X=Cr, Mn) are half-metallic in the Cu2MnAl-type structure. Fe2NiAl has a metallic character in both CuHg2Ti and AlCu2Mn-type structures. The total magnetic moments of the Fe2CrAl and Fe2MnAl compounds are 1.0 and 2.0 μB, respectively, which are in agreement with the Slater-Pauling rule Mtot=Ztot- 24. © 2016 Elsevier B.V. All rights reserved. Source


Mishra R.K.,Mizoram University | Lalneihpuii R.,Mizoram University | Pathak R.,Pachhunga University College
Chemical Physics | Year: 2015

Abstract In the present paper surface tension, Debye temperature, coordination numbers along with microscopic correlations of ten liquid metals are determined using square-well model of correlation functions. Wertheim's solution of the fundamental statistical mechanical equation given by Percus and Yevick for hard spheres is invoked with a square well attractive part as a perturbation tail to get exact solution of the direct correlation function, C(k) in momentum space and the analytical expressions are obtained for structure factor, S(k). These expressions are then used to predict static structure factors for ten liquid metals, leading to fair agreement with experimental data. Radial distribution function g(r) is obtained by Fourier analysis of computed S(k), from which the coordination numbers and the nearest neighbor distances of liquid metals are evaluated. Computed coordination numbers and surface properties of liquid metals using such a simple technique are in good agreement with experimental results. © 2015 Published by Elsevier B.V. Source

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