First-principles investigations of stability, electronic and thermodynamic properties of Ti2FeGe and Ti2FeSn

We present a study of the thermodynamic and physical properties of Ti2FeGe and Ti2FeSn based on the density-functional theory first-principles calculations. Both compounds are found to be half-metallic ferromagnets with a total spin magnetic moment per formula unit of 2.00μB. The stability is evaluated from the physical, chemical and mechanical points of view. The Curie temperature is estimated to be 354 K for Ti2FeGe and 475 K for Ti2FeSn, respectively, which is well-above the room temperature. In addition, the half-metallicity of Ti2FeGe and Ti2FeSn is retained when the lattice constants are changed by −2.6% to 9.7% and −7.1% to 6.9%, respectively. Finally, by using a quasiharmonic Debye model, the Debye temperature, the heat capacity, the coefficient of thermal expansion, and the Grüneisen parameter have also been obtained in the present work. The present calculations show that Ti2FeGe and Ti2FeSn have a great application potential in the spin valve and magnetic tunnel junction.