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Using the spin-polarized relativistic Korringa–Kohn–Rostoker method, we study the electronic and magnetic properties of Fe2NiAs compound with the Hg2CuTi structure. Electronic calculations reveal the d–d orbital hybridization taking an important role in the compound. The calculated magnetic moments, which contain the spin and orbital moments, are primarily carried by Fe atoms located in A and B sites. The orbital moment of Fe2NiAs system is rather small due to the cause of orbital quenching, implying a weak spin–orbit coupling. Simultaneously, we also study the influence of lattice constant on the magnetic moment, it is found that both spin and orbital moments are sensitive to the changes of lattice constants, i.e., the moments become larger as the expansion of lattice constant, indicating the enhancement of spin–orbit coupling effect. In addition, we investigate the magnetic interactions between the constituents to obtain the Heisenberg exchange coupling parameters. It is noted that the interactions are dominated by a strong exchange between Fe atoms. Finally, we acquire the Curie temperatures of Fe2NiAs compound under different lattice constants by using mean field approximation. [ABSTRACT FROM AUTHOR]

Using full-potential local-orbital minimum-basis method within density functional theory, we study the phase transition, electronic and magnetic properties of CsN and RbN alloys under external pressure. Concerning the phase transition, we consider three possible crystal structures, including caesium chloride (CsCl), rock salt (RS) and zinc blende (ZB) ones. Calculations of enthalpy exhibit that a pressure-induced phase transition occurs between the three structures, and the phase transitions are difficult to be distinguished under ambient condition (P = 0 GPa). As the further increase of pressure, they can be specified clearly. In addition, the electronic calculations indicate that both alloys are half-metallic ferromagnets with a total magnetic moment of 2.000 μB, which is promising for fabricating spin injection devices. Finally, we discuss the electronic and magnetic properties of CsN and RbN under external pressure. A pressure-induced delocalized electronic states and magnetic phase transition are observed in RbN and CsN alloys. [ABSTRACT FROM AUTHOR]

Using the spin-polarized relativistic Korringa-Kohn-Rostoker method, we study the electronic, magnetic, and Curie temperature of Fe2-xCoxMnAl alloys. Results indicate that the Fe2-xCoxMnAl alloys preserve the ferromagnetic metallic nature, and the spin polarization is close to 80% when the Co concentration attains to 30%. The calculated total magnetic moment increases linearly as the increase of Co doping concentration, only small changes are observed for Fe(A), Mn(B), and Fe(C) atomic magnetic moments, while for the Al atom, the magnetic moment always nearly approach to zero. The Heisenberg exchange calculations imply that the Co(A)-Mn(B) exchange plays a leading role in interactions, in contrast to the Mn(B)-Mn(B) exchange in pure Fe2MnAl. We further calculate the sum of exchange coupling parameters between the constituents, and evaluate the Curie temperature of Fe2-xCoxMnAl alloys. It is found that the Mn(B)-Mn(B) and Fe/Co(A)-Mn(B) coupling parameters increase evidently with the increase of Co content, and then leading to the Curie temperature above room temperature when the Co doping concentration is over 60%, the change is also in good consistence with calculated total magnetic moment. [ABSTRACT FROM AUTHOR]