Systematic understanding of half-metallicity of ternary compounds in Heusler and Inverse Heusler structures with 3d and 4d elements

Abstract

Employing ab initio electronic structure calculations we extensively study ternary Heusler compounds having the chemical formula X2X Z, where X = Mn, Fe or Co; Z = Al or Si; and X changes along the row of 4d transition metals. A comprehensive overview of these compounds, addressing the trends in structural, electronic, magnetic properties and Curie temperature is presented here along with the search for new materials for spintronics applications. A simple picture of hybridization of the d orbitals of the neighboring atoms is used to explain the origin of the half-metallic gap in these compounds. We show that arrangements of the magnetic atoms in different Heusler lattices are largely responsible for the interatomic exchange interactions that are correlated with the features in their electronic structures as well as possibility of half-metallicity. We find seven half-metallic magnets with 100% spin polarization. We identify few other compounds with high spin polarisation as "near half-metals" which could be of potential use in applications as well. We find that the major features in the electronic structures remain intact if a 3d X constituent is replaced with an isoelectronic 4d, implying that the total number of valence electrons can be used as a predictor of half-metallic nature in compounds from Heusler family.

First‐principles investigations on the ground‐state bulk properties and lattice constant dependent half‐metallic ferrimagnetism of Mn2NbSi full‐Heusler compound

“…Its computed value is listed in Table 1. Clearly, the present result is in excellent agreement with the previously theoretical value [20]. Comparing the total DOS with the partial DOSs, the DOS distribution is mainly considered in three different energy regions.…”

“…A negative value of E f shows the thermodynamical stability of the compound. The present results are in good agreement with the available values for both a 0 and E f [20]. In terms of the a 0 , the mass density ρ of the compound is estimated to be 7.5955 × 10 3 kg/m 3 in this study.…”

“…Meanwhile, the SP total‐energies of both structures are lower than their counterparts. Therefore, the L2 1 structure in the SP state is the most favorable for the full‐Heusler compound from the view of energy, which completely agrees with the previously theoretical result [20].…”

“…However, the investigations on Mn 2 NbZ are rare to the best knowledge of the authors. The ground‐state bulk properties of Mn 2 NbAl, Mn 2 NbSi and Mn 2 NbGa were studied by first‐principles calculations [18–20]. Both Mn 2 NbAl and Mn 2 NbGa were predicted to be true half‐metallic ferrimagnets while Mn 2 NbGa was predicted to possess near half‐metallic ferrimagnetism.…”

Ab-initio study of electronic and magnetic properties of CoIrMnZ (Z = Al, Si, Ga, Ge) Heusler alloys

“…Previous first-principles studies suggest nearly halfmetallic electronic structure in their bulk form. [25][26][27][28][29] In the spin-dependent transport properties of MTJ with Heusler-alloy electrodes and single crystalline MgO barrier, the presence of spin-polarized ∆ 1 -band for the Heusler alloy plays an important role. [32] Therefore, before studying the Heusler-alloy/MgO (001) heterojuntion, it is of extreme interest to discuss the symmetry of the bands crossing the E F along the ∆ axis.…”