Ab Initio Investigations of the Structural, Electronic, Magnetic, and Thermal Properties of Cr 2 TaGe 1-x Sn x Quaternar
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ORIGINAL PAPER
Ab Initio Investigations of the Structural, Electronic, Magnetic, and Thermal Properties of Cr2TaGe1-xSnx Quaternary Heusler Alloys I. Asfour 1 Received: 15 August 2020 / Accepted: 5 November 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The first-principle calculations were performed in the framework of the density functional theory (DFT) using FP-LAPW method as implemented in Wien2k code to determine the structural stability, electronic, and magnetic properties of quaternary Heusler alloys Cr2TaGe1-xSnx (x = 0, 0.25, 0.50, 0.75, 1.00), The results showed that for the compounds, the AlCu2Mnl-type structure is energetically more stable than CuHg2Ti-type structure at the equilibrium volume. The calculated lattice constants for Cr2TaGe and Cr2TaSn are 6.081 Å and 6.311 Å, respectively. For mechanical properties, shear modulus, Young’s modulus, elastic constants, Poisson’s ratio and shear anisotropy factor have studied. Their obtained values reveal that these compounds are mechanically stable. The electronic band structures and density of states of our compounds show a half metallic character with total magnetic moments, − 3.00 μB per formula unit with indirect band gap, 0.569 eV and 0.482 eV for Cr2TaGe and Cr2TaSn respectively. Regarding thermal properties such as the thermal expansion coefficient, heat capacity, and Debye temperature, we have applied a very suitable model for studying thermodynamics quantities called the quasi-harmonic Debye model. On the basis of these results, these alloys are predicted to be good candidates for future spintronic applications. Keywords DFT investigations . Heusler alloys . Gap . Half-metallic . Spintronic
1 Introduction The half-metallic ferromagnets (HMFs) have been intensively investigated during the last decade because of their potential application in spintronics devices [1, 2]. The half-metal properties have been observed in many materials, such as Heusler compounds [3–9]. The history of these materials can be traced back to the year 1903, Fritz Heusler, discovered that a type of formula Cu2MnAl behaves like a ferromagnetic material, although its components are not the magnetic materials in them same [10, 11]. These Heusler alloys present a metallic behavior for a spin band and a semiconductor behavior for the other, they are either ferromagnetic or ferrimagnetic, at Fermi level be the polarization values are important by 100% [12, 13]. Are mainly used in spintronic applications [14] optoelectronic [15],
* I. Asfour [email protected]; [email protected] 1
Département de Technologie des Matériaux, Faculté de physique, Université des Sciences et de la Technologie d’Oran Mohamed Boudiaf (USTO-MB), BP 1505, El M’naouer, 31000 Oran, Algeria
giant magneto resistance spin valve (GMR) [16], thermoelectric [17, 18], superconductivity [19], and spin injection to semiconductors [20–22]. In general, Heusler alloys are determined according to the general formulas X2YZ (Full-Heusler) or XYZ (half-Heusler), where X and Yare
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