Abstract Materials which possess 100% spin-polarization (SP) at their thin-film form are essential for spintronic devices. The half-metallicity has been predicted theoretically in many Co-based Heusler alloys thin-films. Especially the Heusler alloy Co2CrAl has been studied extensively. A previous study reported that the CrAl terminated (001) oriented thin-film had 84% SP, while the other study reported that the CrAl terminated (001) oriented thin-film had 100% SP. Therefore, we investigate in detail the effects of the Fe-doping on the structural, electronic and magnetic properties of the bulk Heusler alloys Co2‒xFexCrAl (x=0.00, 0.25, 0.50, 0.75 or 1.00) and their various terminated (001) oriented thin-films. All the bulk Heusler alloys Co2‒xFexCrAl and their x-CrAl terminated (001) oriented thin-films possess half-metallicity and 100% SP at the Fermi level EF. The surface energy Es of the x-CrAl terminated (001) oriented thin-films increases with Fe-doping concentration x. The CrAl terminated (001) oriented thin-films of the Heusler alloys Co2‒xFexCrAl (x=0.00, 0.25, 0.50, 0.75 or 1.00) maintain the half-metallic (HM) character and 100% SP and thus can be used in spintronic devices, especially the 0.50-CrAl terminated (001) oriented thin-film with the largest spin-down bandgap E g ↓ of 0.213 eV and the largest HM bandgap E g HM of 0.106 eV.

中文翻译：

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Heusler 合金 Co2-xFexCrAl（x=0.00、0.25、0.50、0.75 或 1.00）的 (001) 取向薄膜的带隙工程

摘要 在薄膜形式下具有 100% 自旋极化 (SP) 的材料对于自旋电子器件至关重要。在许多 Co 基 Heusler 合金薄膜中，已经从理论上预测了半金属性。特别是 Heusler 合金 Co2CrAl 已被广泛研究。之前的一项研究报告称，CrAl 终止 (001) 取向的薄膜具有 84% 的 SP，而另一项研究报告称，CrAl 终止 (001) 取向的薄膜具有 100% 的 SP。因此，我们详细研究了 Fe 掺杂对大块 Heusler 合金 Co2-xFexCrAl (x=0.00、0.25、0.50、0.75 或 1.00) 及其各种终止 (001) 取向的结构、电子和磁性能的影响薄膜。所有大块 Heusler 合金 Co2-xFexCrAl 及其 x-CrAl 终止 (001) 取向薄膜都具有费米能级 EF 的半金属度和 100% SP。x-CrAl 终止 (001) 取向薄膜的表面能 Es 随着 Fe 掺杂浓度 x 增加。Heusler 合金 Co2-xFexCrAl (x=0.00、0.25、0.50、0.75 或 1.00) 的 CrAl 终止 (001) 取向薄膜保持半金属 (HM) 特性和 100% SP，因此可用于自旋电子学器件，尤其是 0.50-CrAl 端接 (001) 取向薄膜，其最大自旋向下带隙 E g ↓ 为 0.213 eV，最大 HM 带隙 E g HM 为 0.106 eV。