Browsing by Author "Kashyap, Arti"

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    Effect of the Y element on the structural, electronic and magnetic properties of Heusler compounds Co2YIn (Y = V, Nb, and Ti): An ab initio study
    (AIP Advances, 2021-01-06) Muthui, Zipporah; Musembi, Robinson; Mwabora, Julius; Kashyap, Arti
    We report the effect of varying the Y element on the structural, electronic and magnetic properties of Co2YIn (Y = V, Nb, Ti) Heusler compounds using Density Functional Theory (DFT). The effect of the lattice parameter and total number of valence electrons on spin polarization and the magnetic properties of these Heusler compounds is compared. Co2VIn and Co2NbIn have the same number of valence electrons as Nb and V are from the same group in the periodic table. Co2VIn has almost the same lattice constant as Co2TiIn but they differ in the total number of valence electrons by one, as Ti and V are next neighbors in the same period of the periodic table. The optimized lattice parameters for Co2NbIn and Co2TiIn are found to be 6.20 Å and 6.05 Å respectively, while that of Co2VIn has been reported to be 6.00 Å. Co2NbIn is half metallic with an energy band gap of 0.1 eV in the minority states and has total magnetic moments of 2.02 μB/f.u. very close to the 2.00 μB/f.u. predicted by the Slater-Pauling rule, while Co2TiIn is not half metallic but has a highly spin polarized electronic structure having a spin polarization of 89.59% and total magnetic moments of 1.04μB/f.u. While reducing the number of the valence electrons by one in Co2TiIn has a significant effect on the magnetic moments and spin polarization, an increase in the lattice parameter while maintaining the same number of valence electrons in Co2NbIn does not result in the destruction of the half metallic gap.
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    Structural, Electronic and Magnetic Properties of the Heusler Alloy Mn₂VIn: A Combined DFT and Experimental Study
    (2017-12) Muthui, Zipporah; Musembi, Robinson; Mwabora, Julius Mwakondo; Skomski, Ralph; Kashyap, Arti
    Structural, electronic and magnetic properties of the Heusler alloy Mn₂VIn have been investigated using the density functional theory and experimental techniques. Unlike many other Heusler compounds, Mn₂VIn is not predicted to be half-metallic at the optimized lattice constant, but is highly spin polarized at a slightly lower lattice constant. It however exhibits ferrimagnetic coupling between the Mn and V sublattices, as expected of Mn-based Heuslers. We have, then, synthesized the compound by arc melting and studied magnetic properties that are of interest fundamentally and for technological applications. The structural properties were determined using X-ray diffraction, revealing the presence of cubic and tetragonal phases in the sample. The chemical composition was determined using energy-dispersive X-ray spectroscopy together with the scanning electron microscope, and the magnetic properties were investigated by superconducting quantum interference device magnetometry. The alloy exhibits superparamagnetic spin blocking with a blocking temperature TB of 40 K.