First-principles study on the band structure, magnetic and elastic properties of half-metallic Cr2MnAl

Abstract

In this study, we have investigated the structural, electronic, magnetic and elastic properties of the full-Heusler Cr 2 MnAl alloy in the framework of density functional theory with generalized gradient approximation (GGA). The calculated results showed that Cr 2 MnAl was stable in ferrimagnetic configuration and crystallized in the Hg 2 CuTitype structure. From the band structure and density of states calculation results, we concluded that Cr 2 MnAl belongs to a kind of half-metallic compound with an indirect band gap of 0.37 eV. Immediately thereafter, we have analyzed the origin of half-metallic band gap. The total magnetic moment of Cr 2 MnAl at the stable state is −2 µ B per formula unit, obeying the Slater-Pauling rule Mt = Zt −24. In addition, various mechanical properties have been obtained and discussed based on the three principle elastic tensor elements C 11 , C 12 and C 44 for the first time in the present work. We expect that our calculated results may trigger the application of Cr 2 MnAl in future spintronics field.Mod. Phys. Lett. B Downloaded from www.worldscientific.com by GEORGETOWN UNIVERSITY on 08/21/15. For personal use only. S. Qi et al.observed theoretically or experimentally for half-metallic properties, for example, double perovskites, 6 some oxides, 7,8 dilute magnetic semiconductor 9,10 and materials possessing zincblende structure. 11,12 In fact, investigating and searching for new half-metallic materials are mostly focused on the Heusler alloys due to their diverse physical properties. [13][14][15] Generally, the class of ternary Heusler alloy family includes two possible variations, called half-Heusler and full-Heusler alloy, with chemical formula XYZ and X 2 Y Z, respectively. X and Y represent different transition elements, while Z refers to the main group III, IV or V element. The full-Heusler alloy crystallizes either in the Cu 2 MnAl prototype (space group Fm3(−)m) or in the Hg 2 CuTi prototype (space group F4(−)3m) 16 known as inverse Heusler structure. In the case when the number of 3d valence electrons of Y atom is larger than that of X in full-Heusler alloy, the later structure will be preferred.The first-principles calculation plays a key role due to the fact that many alloys have been initially predicted before their synthesis and integration in realistic devices. Based on the electronic calculations, many Heusler alloys have been predicted half-metallic compounds. Galanakis et al. studied Cr 2 MnZ (Z = P, As, Sb, and Bi) alloys 17 with exactly 24 valence electrons using ab initio electronic structure calculations, and they predicted Cr 2 MnSb as half-metallic fully compensated ferrimagnets (FCFs) with the Curie temperature 342 K. Li et al. investigated the full-Heusler alloys Cr 2 VX (X = Ga, Si, Ge, Sb) 18 and revealed that Cr 2 VSb exhibited a half-metallic nature, yet Cr 2 VSi and Cr 2 VGe showed nearly half-metallic ferromagnetism. Singh et al. studied Cr 2−x Fe x CoAl and Cr 2−x Fe x CoSi to gain 100% spin-polarization. 19 Recently, Skaftouros 20 has proposed Cr 2 Z...

Theoretical Investigation of Electronic Structures, Elastic, and Magnetic Properties of Rh2CrGe Full-Heusler Alloy

“…The shear modulus (G) depicts the resistance of a material to shape change, while the Young modulus determines the resistance against uniaxial tensions. These parameters are important factors to define the mechanical features of a material [35]. We notice that there are no available data to compare with our results of elastic constants, bulk, and shear modulus.…”

“…The study of the elastic properties has an important role to know the nature of the bond between the neighbouring atomic planes, and the elastic constants describing the mechanical stability of the deformation of the crystalline face. It is the proportionality coefficients connecting the applied strain to the stress, which give the response of the material, its strength and mechanical stability under compression [12,34,35]. The computed elastic constants C 11 , C 12 , and C 44 are summarized in Table II.…”

“…The bulk modulus (B) determines the resistance of a material to volume change and reflects its response to a hydrostatic pressure. For cubic material, the shear modulus (G) is related to the second-order elastic constants [35]. The shear modulus (G) depicts the resistance of a material to shape change, while the Young modulus determines the resistance against uniaxial tensions.…”

Pressure dependent structural, elastic and mechanical properties with ground state electronic and optical properties of half-metallic Heusler compounds Cr2YAl (Y=Mn, Co): first-principles study

“…[ 14 ] 0 5.760 0.38 Expt. [ 15 ] 0 5.770 0.55 GGA [ 20 ] 0 5.738 188.958 228.21 GGA This work 5 5.69 184.220 230.18 10 5.66 181.321 257.97 15 5.62 177.504 290.71 20 5.59 174.677 307.98 25 5.56 171.880 313.73 30 5.53 169.112 331.98 Cr 2 MnAl 0 5.831 0.99 GGA [ 5 ] 0 5.850 0.67 GGA [ 17 ] 0 5.866 141.83 0.39 GGA [ 22 ] 0 5.889 204.23 125.29 GGA This work 5 5.82 197.137 159.67 10 5.77 192.100 186.68 …”

“…Another computational study showed that Cr 2 CoAl is a compensated half-metal (CHM) [ 21 ]. There is a DFT study which confirms the half metallicity of Cr 2 MnAl [ 22 ]. According to this study, the magnetic moment calculation of Cr 2 MnAl is consistent with Slater-Pauling rule.…”