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

Crystals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 422 ◽  
Author(s):  
Liyu Hao ◽  
Jiaxue You ◽  
Rabah Khenata ◽  
Yanfeng Wang ◽  
Xiaotian Wang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Total Energy ◽  
Density Of States ◽  
Magnetic Moment ◽  
Tetragonal Phase ◽  
Total Magnetic Moment ◽  
First Principles Calculation ◽  
Tetragonal Structure ◽  
Heusler Compound ◽  
Full Heusler

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.

scholarly journals Spin Gapless Semiconductor–Nonmagnetic Semiconductor Transitions in Fe-Doped Ti2CoSi: First-Principle Calculations

2018 ◽  
Vol 8 (11) ◽  
pp. 2200 ◽  
Author(s):  
Yu Feng ◽  
Zhou Cui ◽  
Ming-sheng Wei ◽  
Bo Wu ◽  
Sikander Azam
Keyword(s):  
Magnetic Moment ◽  
Electronic Structures ◽  
Magnetic Moments ◽  
Total Magnetic Moment ◽  
First Principle ◽  
Half Metallic ◽  
Heusler Compound ◽  
First Principle Calculations ◽  
Metallic Ferromagnet

Employing first-principle calculations, we investigated the influence of the impurity, Fe atom, on magnetism and electronic structures of Heusler compound Ti2CoSi, which is a spin gapless semiconductor (SGS). When the impurity, Fe atom, intervened, Ti2CoSi lost its SGS property. As TiA atoms (which locate at (0, 0, 0) site) are completely occupied by Fe, the compound converts to half-metallic ferromagnet (HMF) TiFeCoSi. During this SGS→HMF transition, the total magnetic moment linearly decreases as Fe concentration increases, following the Slate–Pauling rule well. When all Co atoms are substituted by Fe, the compound converts to nonmagnetic semiconductor Fe2TiSi. During this HMF→nonmagnetic semiconductor transition, when Fe concentration y ranges from y = 0.125 to y = 0.625, the magnetic moment of Fe atom is positive and linearly decreases, while those of impurity Fe and TiB (which locate at (0.25, 0.25, 0.25) site) are negative and linearly increase. When the impurity Fe concentration reaches up to y = 1, the magnetic moments of Ti, Fe, and Si return to zero, and the compound is a nonmagnetic semiconductor.

Structural and Magnetic Study on the Effect of Substitution of Cobalt by d-Valent Elements of Co2FeSi Heusler Alloy

2016 ◽  
Vol 708 ◽  
pp. 37-41
Author(s):  
Muhammad Noor Syazwan Saimin ◽  
Siti Sumaiyah Sheikh Abdul Aziz ◽  
A.M.M. Ali ◽  
Oskar Hasdinor Hassan ◽  
Muhd Zu Azhan Yahya ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
Band Structure ◽  
Fermi Level ◽  
Density Of States ◽  
Magnetic Moment ◽  
Local Magnetic Moment ◽  
Half Metallic ◽  
New States ◽  
Full Heusler

In this paper, the effect of substitution of Co by d-valent elements such as Ag and Pt on electronic structure and magnetic properties of full Heusler type Co2FeSi alloys was investigated. Structural study reveals the presence of a small gap in the minority band structure around the vicinity of the Fermi level on Co2FeSi resulting to half-metallic behaviour. However, CoFeSiAg and CoFeSiPt cannot preserved the half-metalicity due to disappearing of the gap in the minority band structure due to the creation of new states around the Fermi level in the minority density of states. The variation in the magnetic moment of Co2FeSi with change of the atoms was attributed to the change in the local magnetic moment of atoms.

scholarly journals Structural configuration and tetragonal phase stability in the equiatomic quaternary Heusler compound TiZnMnSi

RSC Advances ◽  
2020 ◽  
Vol 10 (65) ◽  
pp. 39731-39738
Author(s):  
Jiaying Ji ◽  
Qijia Gu ◽  
Rabah Khenata ◽  
Fayang Guo ◽  
Yanfeng Wang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Phase Stability ◽  
Tetragonal Phase ◽  
Strong Tendency ◽  
Structural Configuration ◽  
Heusler Compound ◽  
Quaternary Heusler Compound

The equiatomic quaternary Heusler compound TiZnMnSi exhibits strong tendency to tetragonal phase transformation.

scholarly journals Theoretical Study of the Electronic, Magnetic, Mechanical and Thermodynamic Properties of the Spin Gapless Semiconductor CoFeMnSi

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 678 ◽  
Author(s):  
Xingwen Tan ◽  
Jiaxue You ◽  
Peng-Fei Liu ◽  
Yanfeng Wang
Keyword(s):  
Mechanical Properties ◽  
Thermodynamic Properties ◽  
Magnetic Moment ◽  
Elastic Anisotropy ◽  
Theoretical Calculations ◽  
Research Direction ◽  
Debye Model ◽  
Total Magnetic Moment ◽  
First Principles Calculation ◽  
Shear Moduli

CoFeMnSi has been both experimentally and theoretically proven as a novel spin-gapless semiconductor and resulted in a new research direction in equiatomic full Heusler compounds. Using the first-principles calculation method, we investigated the electronic, magnetic and mechanical properties of CoFeMnSi material in this study. The obtained lattice constant under the LiMgPdSn-type Heusler structure is 5.611 Å and it is fairly consistent with previous experimental results and theoretical calculations. Furthermore, the achieved total magnetic moment of 4 μB follows the Slater–Pauling rule as Mtotal = Ztotal − 24, where Mtotal is the total magnetic moment per formula unit and Ztotal is the total valence electron number, i.e., 28 for CoFeMnSi material. We have also examined the mechanical properties of CoFeMnSi and computed its elastic constants and various moduli. Results show CoFeMnSi behaves in a ductile fashion and its strong elastic anisotropy is revealed with the help of the 3D-directional-dependent Young’s and shear moduli. Both mechanical and dynamic stabilities of CoFeMnSi are verified. In addition, strain effects on the electronic and magnetic properties of CoFeMnSi have been investigated, including both uniform and tetragonal strains, and we found that the spin-gapless feature is easily destroyed with both strain conditions, yet the total magnetic moment maintains a good stability. Furthermore, the specific behaviors under various temperatures and pressures have been accessed by the thermodynamic properties with a quasi-harmonic Debye model, including bulk modulus, thermal expansion coefficient, Grüneisen constant, heat capacity and Debye temperature. This comprehensive study can offer a very helpful and valuable reference for other relative research works.

Effect of strain on the magnetism of Fe-doped MoTe2 monolayer

2019 ◽  
Vol 33 (25) ◽  
pp. 1950304 ◽  
Author(s):  
Murong Zhang ◽  
Xiaojun Wang ◽  
Xin Wang ◽  
Ying Wang ◽  
Mingyan Wei ◽  
...  
Keyword(s):  
Density Of States ◽  
Magnetic Moment ◽  
First Principles ◽  
Tensile Strain ◽  
Compressive Strain ◽  
First Principles Calculation ◽  
Biaxial Strain

First-principles calculation has been performed to investigate the effect of strain on the magnetic moment of Fe-doped MoTe2 monolayer. Our results show that the Fe-doped MoTe2 monolayer is semiconductor with the magnetic moment of 2.037 [Formula: see text]. By analyzing the density of states, we find that the magnetic moment is mainly contributed by the Fe atom. When the biaxial strain is applied along the layer, the results show that the magnetic moment is almost unchanged when the compressive strain is under 5% and tensile strain is under 7%. However, as the strain increases, the magnetic moment decreases to almost zero with compressive strain larger than 7%, and the magnetic moment begins to increase with the tensile strain larger than 8%, which indicates the different effects of compressive strain and tensile strain on the magnetism of Fe-doped MoTe2.

Ferroelectric Domain Structure of Pb(Zr.52Ti.48)03

1980 ◽  
Vol 38 ◽  
pp. 214-215
Author(s):  
E.K. Goo ◽  
R.K. Mishra
Keyword(s):  
Phase Transformation ◽  
Domain Structure ◽  
Tetragonal Phase ◽  
Ferroelectric Domain ◽  
Cubic Phase ◽  
Ion Milling ◽  
Thin Foils ◽  
Ferroelectric Domain Structure ◽  
Ferroelectric Domains

Ferroelectric domains are twins that are formed when PZT undergoes a phase transformation from a non-ferroelectric cubic phase to a ferroelectric tetragonal phase upon cooling below ∼375°C.,1 The tetragonal phase is spontaneously polarized in the direction of c-axis, making each twin a ferroelectric domain. Thin foils of polycrystalline Pb (Zr.52Ti.48)03 were made by ion milling and observed in the Philips EM301 with a double tilt stage.

Phase transformation and preferred orientation in carboxylate derived ZrO2 thin films on silicon substates

1992 ◽  
Vol 7 (11) ◽  
pp. 3065-3071 ◽  
Author(s):  
Peir-Yung Chu ◽  
Isabelle Campion ◽  
Relva C. Buchanan
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Phase Transformation ◽  
Heating Rate ◽  
Tetragonal Phase ◽  
Monoclinic Phase ◽  
Preferred Orientation ◽  
Si Substrate ◽  
Interfacial Diffusion ◽  
Deposited Films

Phase transformation and preferred orientation in ZrO2 thin films, deposited on Si(111) and Si(100) substrates, and prepared by heat treatment from carboxylate solution precursors were investigated. The deposited films were amorphous below 450 °C, transforming gradually to the tetragonal and monoclinic phases on heating. The monoclinic phase developed from the tetragonal phase displacively, and exhibited a strong (111) preferred orientation at temperature as low as 550 °C. The degree of preferred orientation and the tetragonal-to-monoclinic phase transformation were controlled by heating rate, soak temperature, and time. Interfacial diffusion into the film from the Si substrate was negligible at 700 °C and became significant only at 900 °C, but for films thicker than 0.5 μm, overall preferred orientation exceeded 90%.

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