Abstract This investigation consists of performing the structural, thermodynamic, electronic, magnetic and thermoelectric characteristics of the quaternary Heusler CoNbMnX (X = Al, Si) alloys using DFT within Wien2k code. Our calculations show that the atomic arrangement of the two alloys CoNbMnAl and CoNbMnSi is Type-I. From the elastic constant and the formation energy values, these compounds are predicted to be mechanically and thermodynamically stable, thus can be formed experimentally. The calculated values of their bulk modulus and cohesive energy values show that CoNbMnSi is more rigid than CoNbMnAl. From the analysis of the electronic properties, CoNbMnAl is identified to be paramagnetic and semiconductor alloy with 0.15 eV narrow indirect (Γ-X) band gap. Whereas, CoNbMnSi is characterized as a ferromagnetic alloy with half-metallicity character having a total magnetic moment of 1μB. The charge density contours and Fermi surface, predict a combined covalent and ionic bond between the atoms of CoNbMnX alloys. The calculated thermoelectric parameters assume that these alloys tend to behave as p-type with the same thermoelectric efficiency for either charge carriers; hole or electron. Depending on the high Seebeck coefficient value and ZT = 1 of the present alloys, potential applications are predicted, such as spin injection materials and spintronic applications.

中文翻译：

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四元 CoNbMnX (X = Al, Si) Heusler 合金的结构、热弹性、电磁和热电属性

摘要 本研究包括在 Wien2k 代码中使用 DFT 执行四元 Heusler CoNbMnX (X = Al, Si) 合金的结构、热力学、电子、磁和热电特性。我们的计算表明，两种合金 CoNbMnAl 和 CoNbMnSi 的原子排列是 I 型。根据弹性常数和形成能值，预测这些化合物在机械和热力学上是稳定的，因此可以通过实验形成。它们的体积模量和内聚能值的计算值表明 CoNbMnSi 比 CoNbMnAl 更坚硬。从电子特性的分析中，CoNbMnAl 被确定为具有 0.15 eV 窄间接 (Γ-X) 带隙的顺磁性半导体合金。然而，CoNbMnSi 是一种铁磁合金，具有半金属性特征，总磁矩为 1μB。电荷密度等高线和费米面预测了 CoNbMnX 合金原子之间的组合共价键和离子键。计算出的热电参数假设这些合金往往表现为 p 型，对于任一电荷载流子具有相同的热电效率；空穴或电子。根据本合金的高塞贝克系数值和 ZT = 1，预测了潜在的应用，例如自旋注入材料和自旋电子应用。计算出的热电参数假设这些合金往往表现为 p 型，对于任一电荷载流子具有相同的热电效率；空穴或电子。根据本合金的高塞贝克系数值和 ZT = 1，预测了潜在的应用，例如自旋注入材料和自旋电子应用。计算出的热电参数假设这些合金往往表现为 p 型，对于任一电荷载流子具有相同的热电效率；空穴或电子。根据本合金的高塞贝克系数值和 ZT = 1，预测了潜在的应用，例如自旋注入材料和自旋电子应用。