Investigations of the half-metallic behavior and the magnetic and thermodynamic properties of half-Heusler CoMnTe and RuMnTe compounds: A first-principles study

Abstract

First-principles spin-polarized density functional theory (DFT) investigations of the structural, electronic, magnetic, and thermodynamics characteristics of the half-Heusler, CoMnTe and RuMnTe compounds are carried out. Calculations are accomplished within a state of the art full-potential (FP) linearized (L) augmented plane wave plus a local orbital (APW + lo) computational approach framed within DFT. The generalized gradient approximation (GGA) parameterized by Perdew, Burke, and Ernzerhof (PBE) is implemented as an exchange correlation functional as a part of the total energy calculation. From the analysis of the calculated electronic band structure as well as the density of states for both compounds, a strong hybridization between d states of the higher valent transition metal (TM) atoms (Co, Ru) and lower valent TM atoms of (Mn) is observed. Furthermore, total and partial density of states (PDOS) of the ground state and the results of spin magnetic moments reveal that these compounds are both stable and ideal half-metallic ferromagnetic. The effects of the unit cell volume on the magnetic properties and half-metallicity are crucial. It is worth noting that our computed results of the total spin magnetic moments, for CoMnTe equal to 4 µB and 3 µB per unit cell for RuMnTe, nicely follow the rule µ tot = Z t − 18. Using the quasi-harmonic Debye model, which considers the phononic effects, the effecs of pressure P and temperature T on the lattice parameter, bulk modulus, thermal expansion coefficient, Debye temperature, and heat capacity for these compounds are investigated for the first time.

Structural, electronic and magnetic properties of the manganese telluride layers AMnTe2 (A = K, Rb, Cs) from first-principles calculations

“…Zt of valence electrons in the f.u. [6,15,25]. In the compounds under study the form of this rule is = Zt -22 as we will discuss in detail in the following.…”

“…Also, although the lattice is tetragonal, since the atoms sit at sites of tetrahedral symmetry, the symmetry arguments presented in Refs. [6,15,25] for the full-Heusler compounds are still valid taking into account that the z-axis is no longer equivalent to the x-and y-axis and thus for example the triple degenerate p-states will break into two double degenerate at the Γ point (px and py) states and a single pz state.…”

“…follows the so-called Slater-Pauling behavior showing a linear variation with the total number Zt of valence electrons in the f.u. [6,15,25]. In the compounds under study the form of this rule is 𝜇 𝑡𝑜𝑡 = Zt -22 as we will discuss in detail in the following.…”

“…We should note that irrespectively of the orbitals which the valence electrons occupy in the free atoms, in the solids they occupy each time the lowest available electronic bands which may be of different orbital character as shown in Refs. [6,15,25]. Also, although the lattice is tetragonal, since the atoms sit at sites of tetrahedral symmetry, the symmetry arguments presented in Refs.…”

Half-metallicity of the bulk and (001) surface of NbFeCrAl and NbFeVGe Heusler compounds: a first-principles prediction

“…, where the M t and Z t represent for the total magnetic moment and the number of total valence electrons in per unit cell, respectively. 29,40,41 Very recently, some HM materials containing 4d transition metal elements, for example, Zr-based, 2,40,[42][43][44][45][46][47][48][49][50][51][52][53] Ru-based 54 and Rh-based 55 Heusler compounds, have been predicted widely by rst-principles calculations. To the best of our knowledge, experiments of a few quaternary Heusler compounds containing 4d elements, such as CoRhMnZ (Z ¼ Ga, Sn, Sb) and the alloy Co 0.5 Rh 1.5 MnSb, 56 have been investigated, but other researches currently are focused on prediction theoretically for HM materials.…”