Origin of the Tetragonal Ground State of Heusler Compounds

Faleev, Sergey V.; Ferrante, Yari; Jeong, Jaewoo; Samant, Mahesh G.; Jones, Barbara; Parkin, Stuart S. P.

doi:10.1103/physrevapplied.7.034022

Cited by 144 publications

(90 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, the L21-type structure is formed for Pd2CoAl. After the crystal structural configuration of Pd2CoAl has been determined, we further calculated its equilibrium lattice by polynomial fitting and minimization searching of the total energy and the derived equilibrium lattice is 6.057 Å, see Table 1, which coincides very well with previous study [30,34].…”

Section: Crystal Structure and Equilibrium Latticesupporting

confidence: 80%

“…However, the two strong spin split distribution areas in the austenitic phase have been compressed into much wider and shallower ones in the martensitic phase, which means the strong d-d hybridization and exchange splitting in the cubic phase have been weakened in the tetragonal phase. As suggested by previous study [30], the density of states at the Fermi energy plays an important role in regulating the phase stability. Thus, we further provide the values of states in the two spin directions for both phases at the Fermi level, as shown in the right vertical axis in Figure 8.…”

Section: Tetragonal Structure and Phase Stabilitymentioning

confidence: 67%

“…In full Heusler compounds with possible phase transformation, the Bain paths have been widely utilized to study the reversible structural transformation between the austenitic and martensitic phases. A recent comprehensive theoretical study [30] of 286 full Heusler alloys from Faleev et al has found that 62% have tetragonal ground states at zero temperature, including 15 Pd 2 -based full Heusler compounds. It is also well known that the physical properties of solid crystals are strongly related with the corresponding structures.…”

Section: Tetragonal Structure and Phase Stabilitymentioning

confidence: 99%

“…Normally, Heusler compounds have highly ordered cubic crystal structures with different atomic ordering configurations. However, several recent studies have found many Heusler materials have tetragonal structure as the ground state, e.g., Felser et al [29] found that Mn 3-x Fe x Ga and Mn 3-x Co x Ga have tetragonal structure over the whole range of compositions from experiment results, and then Faleev et al [30,31] performed an extensive investigation on the origin of the tetragonal ground state for 286 Heusler compounds by theoretical calculation, which shows 62% have tetragonal structure. More recently, Han et al [32,33] and Wu et al [34] studied the phase competition between cubic and tetragonal structures in a series of conventional Heusler compounds Pd 2 YZ (Y = Co, Fe, Mn; Z = B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, P, As, Sb) and all-d-metal Heusler compounds X 2-x Mn 1+x V (X = Pd, Ni, Pt, Ag, Au, Ir, Co; x = 1, 0) and Zn 2 MMn (M = Ru, Rh, Pd, Os, Ir) and found that many of them also exhibit tetragonal phases, especially the most of Pd 2 Co-based Heusler alloys.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Theoretical Study of the Electronic and Magnetic Properties and Phase Stability of the Full Heusler Compound Pd2CoAl

et al. 2019

View full text Add to dashboard Cite

Based on first principles calculation, a systematical investigation has been performed to study the electronic, magnetic, dynamic, and mechanical properties of the full Heusler compound Pd2CoAl. It is found that the L21-type structure is energetically more stable than the XA-type due to the lower total energy. The obtained lattice constant in cubic ground state is 6.057 Å, which matches well with previous study. The calculated electronic band structure reveals the metallic nature of Pd2CoAl and its total magnetic moment of 1.78 μB is mainly contributed by Co atom from strong spin splitting effect, as indicated with the distinctive distributions of the density of states in two spin directions. Under uniform strains from −5% to +5%, the variation of total magnetic moment has been obtained and it is still caused by the much larger change from Co atom, compared with Pd and Al atoms. The tetragonal structure has further been analyzed and we found that there is possible martensitic phase transformation because the total energy can be further reduced when the cubic structure is varied into the tetragonal one. The large energy difference of 0.165 eV between the tetragonal and cubic phases is found at the c/a ratio of 1.30. The total density of states has been compared between the cubic and tetragonal phases for Pd2CoAl and results show tetragonal phase transformation could reduce the states at the Fermi energy level in both directions. In addition, the dynamic and mechanical stabilities have also been evaluated for Pd2CoAl in both cubic and tetragonal structures and results confirm that the tetragonal phase shows good stability against the cubic phase, which further verifies that the tetragonal phase transformation is highly expected. In the end, the strong elastic anisotropy in the tetragonal structure has been clearly shown with the calculated directional dependence of the Young’s modulus and shear modulus.

show abstract

Section: Crystal Structure and Equilibrium Latticesupporting

confidence: 80%

Section: Tetragonal Structure and Phase Stabilitymentioning

confidence: 67%

Section: Tetragonal Structure and Phase Stabilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Theoretical Study of the Electronic and Magnetic Properties and Phase Stability of the Full Heusler Compound Pd2CoAl

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Ru 2 TGa (T = Cr, Mn, and Co) Heusler alloys have been the subject of few theoretical and experimental studies. [23][24][25][26][27][28][29][30] Experimentally, the standard enthalpies of formation, lattice parameters, and phase transitions of Ru 2 YZ (Y = Mn, Co, Fe, Hf, Rh, Ti, V, Zr; Z = Ga, Al, In, Si, Ge, Sn) Heusler compounds were analyzed by Yin and Nash. 23 They measured standard formation enthalpy for the Ru 2 MnGa alloy by employing direct reaction calorimetry at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Magnetic, Electronic, Mechanic, Anisotropic Elastic and Vibrational Properties of Antiferromagnetic Ru2TGa (T = Cr, Mn, and Co) Heusler Alloys

Candan

2019

Journal of Elec Materi

View full text Add to dashboard Cite

A theoretical study of magnetic, electronic, mechanic, anisotropic elastic, and vibrational properties of Ru 2 TGa (T = Cr, Mn, and Co) Heusler alloys has been extensively investigated by the first-principles method using the generalized gradient approximation. Structural parameters such as lattice constant (a 0), bulk modulus (B) and first pressure derivative of bulk modulus (B¢) were obtained by using the Murnaghan equation. The calculated formation enthalpies (DH f) showed that these alloys are thermodynamically stable. The total spin magnetic moments per unit cell of Ru 2 TGa (T = Cr, Mn, and Co) alloys were found to be 1.16 l B , 2.16 l B and 0.29 l B , respectively. In addition to electronic band structures along the high symmetry directions, corresponding total and partial density of states were also plotted. It was found that the spin-up states have a metallic character for all alloys, but the spin-down states of the other alloys except for Ru 2 CoGa have a pseudo-gap at the Fermi level. The bulk modulus (B), shear modulus (G), ratio of B/G, Young's modulus (E), Poisson's ratios (m), Vickers hardness (H V), sound velocities (v l , v t , and v m), Debye temperatures (H D) and melting temperatures (T melt) were obtained from elastic constants (C ij) in accordance with the Voigt-Reuss-Hill approximation. The calculated elastic constants showed that these alloys are mechanically stable and they have anisotropic character. The elastic anisotropy of the considered alloys was analyzed and pictured in great detail with 2D and 3D figures of directional dependence of Young's modulus, linear compressibility, shear modulus, and Poisson's ratio.These alloys are dynamically stable because there are no negative modes in their phonon dispersion curves.

show abstract

A New Highly Anisotropic Rh‐Based Heusler Compound for Magnetic Recording

Fecher

et al. 2020

Advanced Materials

View full text Add to dashboard Cite

The development of high‐density magnetic recording media is limited by superparamagnetism in very small ferromagnetic crystals. Hard magnetic materials with strong perpendicular anisotropy offer stability and high recording density. To overcome the difficulty of writing media with a large coercivity, heat‐assisted magnetic recording was developed, rapidly heating the media to the Curie temperature Tc before writing, followed by rapid cooling. Requirements are a suitable Tc, coupled with anisotropic thermal conductivity and hard magnetic properties. Here, Rh2CoSb is introduced as a new hard magnet with potential for thin‐film magnetic recording. A magnetocrystalline anisotropy of 3.6 MJ m−3 is combined with a saturation magnetization of μ0Ms = 0.52 T at 2 K (2.2 MJ m−3 and 0.44 T at room temperature). The magnetic hardness parameter of 3.7 at room temperature is the highest observed for any rare‐earth‐free hard magnet. The anisotropy is related to an unquenched orbital moment of 0.42 μB on Co, which is hybridized with neighboring Rh atoms with a large spin–orbit interaction. Moreover, the pronounced temperature dependence of the anisotropy that follows from its Tc of 450 K, together with a thermal conductivity of 20 W m−1 K−1, make Rh2CoSb a candidate for the development of heat‐assisted writing with a recording density in excess of 10 Tb in.−2.

show abstract

Origin of the Tetragonal Ground State of Heusler Compounds

Cited by 144 publications

References 23 publications

Theoretical Study of the Electronic and Magnetic Properties and Phase Stability of the Full Heusler Compound Pd2CoAl

Theoretical Study of the Electronic and Magnetic Properties and Phase Stability of the Full Heusler Compound Pd2CoAl

Magnetic, Electronic, Mechanic, Anisotropic Elastic and Vibrational Properties of Antiferromagnetic Ru2TGa (T = Cr, Mn, and Co) Heusler Alloys

A New Highly Anisotropic Rh‐Based Heusler Compound for Magnetic Recording

Contact Info

Product

Resources

About