To find new spin-gapless semiconductors (SGSs) or half-metallic materials to promote the development of spintronics, the stable, electronic, magnetic, and mechanical properties of quaternary Heusler alloys CoX′CrZ (X′ = Sc, Ti; Z = Al, Ga) are studied by first principles. Findings show the ground state structure of all alloys is the T-II structure, and their equilibrium lattice constants are CoScCrAl (6.15 Å), CoScCrGa (6.14 Å), CoTiCrAl (5.94 Å), and CoTiCrGa (5.93 Å), respectively, indicating that the T-II structure is easily synthesized. The new SGSs of CoScCrAl and CoScCrGa have an indirect bandgap at the Fermi level in spin-down channels. The indirect bandgap values are 0.52 and 0.56 eV, respectively, and the origin of the bandgap is analyzed. The spin polarization of all alloys is more than 90%, and CoScCrAl and CoScCrGa are suitable for room temperature applications due to their high Curie temperature and strict compliance with the Slater–Pauling rule. CoTiCrAl and CoTiCrGa conform to the Slater–Pauling rule when the lattice constant reaches 6.30 Å, and the half-metallicity can be improved by doping or strain. All alloys have unique mechanical properties and are mechanically stable. Moreover, CoScCrAl and CoScCrGa exhibit brittle behavior, whereas CoTiCrAl and CoTiCrGa exhibit ductility.

中文翻译：

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CoX'CrZ (X' = Sc, Ti; Z = Al, Ga) 四元赫斯勒合金的结构、电子、磁性和弹性特性：第一性原理研究

寻找新的自旋无隙半导体 (SGSs) 或半金属材料以促进自旋电子学的发展，四元赫斯勒合金 CoX'CrZ (X' = Sc, Ti; Z = Al , Ga) 是由第一性原理研究的。结果表明，所有合金的基态结构均为 T-II 结构，其平衡晶格常数分别为 CoScCrAl (6.15 Å)、CoScCrGa (6.14 Å)、CoTiCrAl (5.94 Å) 和 CoTiCrGa (5.93 Å)，表明T-II 结构很容易合成。CoScCrAl 和 CoScCrGa 的新 SGS 在自旋向下通道中具有费米能级的间接带隙。间接带隙值分别为 0.52 和 0.56 eV，分析了带隙的起源。所有合金的自旋极化率都在90%以上，CoScCrAl 和 CoScCrGa 因其居里温度高且严格遵守 Slater-Pauling 规则而适用于室温应用。当晶格常数达到 6.30 Å 时，CoTiCrAl 和 CoTiCrGa 符合 Slater-Pauling 规则，并且可以通过掺杂或应变来改善半金属性。所有合金都具有独特的机械性能并具有机械稳定性。此外，CoScCrAl 和 CoScCrGa 表现出脆性行为，而 CoTiCrAl 和 CoTiCrGa 表现出延展性。