Magnetism in Yttrium Intermetallics Ab Initio Stu

Authors: Ramesh Sharma Yamini Sharma

Publish Date: 2016/11/09

Volume: 30, Issue: 4, Pages: 1003-1018

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Abstract

This work is stimulated by the recent developments in the search of novel magnetic materials such as the simple cubic laves phase compounds of yttrium and 3d transition metals with ferromagnetic or exchange enhanced Pauli paramagnetic properties The ground state electronic structure of the intermetallics was calculated by the full potential linearized augmented plane wave method FPLAPW based on the density functional theory The suitability of the various approximations LDA and GGA with exchangecorrelations XCs potentials such as GGAPBEsol GGAWC etc on the electronic structure was also investigated From the calculated band structure and angularmomentum projected density of states DOS strong d–d hybridization of electrons at the Fermi level was observed The FeY and CoY coupling is stronger for minority component of Fe/Co d states which leads to formation of negative magnetic moment on Y sites The magnetic moments were found to be considerably larger than the experimental moments although there is good agreement with methods based on DFT The YTM compounds have mixed chemical bonding character which we have characterized by calculating the Bader charge distributions electron localization function as well as the magnetization spin density High magnetization density is localized on the Fe atoms which imparts ferromagnetism to the more ionic YFe2 system whereas the shift of electron density and magnetization density towards inter atomic regions imparts exchange enhanced paramagnetic properties in more covalent YCo2 system In order to study the influence of delectrons the temperaturedependent electrical resistivity and thermopower were obtained from the band energies Magnetism was investigated in terms of enhanced magnetic susceptibility and Sommerfeld term γ obtained from low temperaturespecific heats The dynamical stability of YX2 was investigated by calculating the vibrational phonon modes and phonon density of states The lowermost frequency modes arise from vibrations of Y–Fe bonds which exhibit structural instability which have been interpreted in terms of electronphonon coupling The coupling of magnetic moments with the lattice in YFe2 verifies the magnetoelastic interactions found experimentally

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