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<p>This study investigates the structural, elastic, dynamic, magnetic, and electronic properties of the Co<sub>2</sub>CrTi<sub><i>x</i></sub>V<sub>1−<i>x</i></sub> full-Heusler alloys using first-principles calculations. We analyze the competition between the ferromagnetic regular (L2<sub>1</sub>) and inverse (XA) structures derived from the parent compounds Co<sub>2</sub>CrV and Co<sub>2</sub>CrTi. Our findings reveal that the L2<sub>1</sub> structure is energetically favorable for the Co<sub>2</sub>CrV and Co<sub>2</sub>CrTi, full-Heusler alloys, with equilibrium lattice constants of 5.761&#xa0;Å and 5.854&#xa0;Å, respectively, compared to the inverse XA structure. The cohesive energy, while not explicitly quantified, is implied by the strong atomic bonding in the L2<sub>1</sub> configuration, contributing to the alloy’s stability. Formation energies for the Co<sub>2</sub>CrTi<sub><i>x</i></sub>V<sub>1−<i>x</i></sub> alloys (<i>x</i> = 0.25, 0.5, 0.75, 1) are negative at − 0.035&#xa0;eV, -0.075&#xa0;eV, − 0.114&#xa0;eV, and − 0.153&#xa0;eV, respectively, confirming thermodynamic stability for <i>x</i> ≥ 0.25.</p><p>Mechanically, the alloys satisfy the Born stability criteria, with elastic constants for <i>x</i> = 1 being <i>C</i><sub>11</sub> = 258&#xa0;GPa, <i>C</i><sub>12</sub> = 149&#xa0;GPa, and <i>C</i><sub>44</sub> = 108&#xa0;GPa, shear moduli of 75–82&#xa0;GPa, and Young’s modulus peaking at 215 GPa, indicating enhanced stiffness. Ductility is evidenced by a Pugh’s ratio &lt; 0.57 (e.g., 0.44 for <i>x</i> = 1) and a Poisson’s ratio of 0.31–0.34. Dynamically, alloys with <i>x</i> ≥ 0.5 show no negative phonon frequencies, while those with <i>x</i> = 0 and 0.25 exhibit potential instability due to weak soft modes at the Γ point; heat capacity approaches ~ 25&#xa0;J/mol·K at 300&#xa0;K (<i>e.g</i>., 22.96&#xa0;J/mol·K for <i>x</i> = 1).</p><p>Magnetically, the alloys are ferromagnetic, with total magnetic moments decreasing from 4.83&#xa0;<i>μ</i><sub>B</sub> (<i>x</i> = 0)–4.06&#xa0;<i>μ</i><sub>B</sub> (<i>x</i> = 1), transitioning to half-metallic behavior at <i>x</i> = 1. Electronically, spin-polarized density of states calculations indicate conductive behavior in the majority spin channel, primarily from Cr-3<i>d</i> states with minor Co-3<i>d</i> contributions, while Ti-3<i>d</i> states contribute negligibly near the Fermi level; increasing Ti content reduces the density of states near the Fermi level, achieving half-metallicity in Co<sub>2</sub>CrTi. These findings elucidate the potential of the Co<sub>2</sub>CrTi<sub><i>x</i></sub>V<sub>1−<i>x</i></sub> alloys for spintronics and magnetic applications, addressing gap in theoretical and experimental data.</p>

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Investigating the dynamic stability and magnetic properties of Co2CrTixV1−x full-heusler alloys: a first-principles approach

  • 期刊论文

  • 发表日期：

    2025年11月20日

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  • I. Hamri,
  • Y. Zaoui,
  • L. Beldi,
  • H. Bendaoud,
  • S. Amari,
  • M. Z. Chekroun,
  • B. Bouhafs

摘要

This study investigates the structural, elastic, dynamic, magnetic, and electronic properties of the Co2CrTixV1−x full-Heusler alloys using first-principles calculations. We analyze the competition between the ferromagnetic regular (L21) and inverse (XA) structures derived from the parent compounds Co2CrV and Co2CrTi. Our findings reveal that the L21 structure is energetically favorable for the Co2CrV and Co2CrTi, full-Heusler alloys, with equilibrium lattice constants of 5.761 Å and 5.854 Å, respectively, compared to the inverse XA structure. The cohesive energy, while not explicitly quantified, is implied by the strong atomic bonding in the L21 configuration, contributing to the alloy’s stability. Formation energies for the Co2CrTixV1−x alloys (x = 0.25, 0.5, 0.75, 1) are negative at − 0.035 eV, -0.075 eV, − 0.114 eV, and − 0.153 eV, respectively, confirming thermodynamic stability for x ≥ 0.25.

Mechanically, the alloys satisfy the Born stability criteria, with elastic constants for x = 1 being C11 = 258 GPa, C12 = 149 GPa, and C44 = 108 GPa, shear moduli of 75–82 GPa, and Young’s modulus peaking at 215 GPa, indicating enhanced stiffness. Ductility is evidenced by a Pugh’s ratio < 0.57 (e.g., 0.44 for x = 1) and a Poisson’s ratio of 0.31–0.34. Dynamically, alloys with x ≥ 0.5 show no negative phonon frequencies, while those with x = 0 and 0.25 exhibit potential instability due to weak soft modes at the Γ point; heat capacity approaches ~ 25 J/mol·K at 300 K (e.g., 22.96 J/mol·K for x = 1).

Magnetically, the alloys are ferromagnetic, with total magnetic moments decreasing from 4.83 μB (x = 0)–4.06 μB (x = 1), transitioning to half-metallic behavior at x = 1. Electronically, spin-polarized density of states calculations indicate conductive behavior in the majority spin channel, primarily from Cr-3d states with minor Co-3d contributions, while Ti-3d states contribute negligibly near the Fermi level; increasing Ti content reduces the density of states near the Fermi level, achieving half-metallicity in Co2CrTi. These findings elucidate the potential of the Co2CrTixV1−x alloys for spintronics and magnetic applications, addressing gap in theoretical and experimental data.