Muhammad Iltaf, Zhang Jian-Min, Ali Anwar, Mushtaq Muhammad, Muhammad Suleman
College of Physics and Information Technology, Shaanxi Normal University, Xian 710119, Shaanxi, People's Republic of China.
Department of Physics, Women University of Azad Jammu & Kashmir, Bagh, 12500, Pakistan.
J Phys Condens Matter. 2020 May 15;32(32). doi: 10.1088/1361-648X/ab832d.
Thin films with stable half-metallic (HM) character and 100% spin-polarization (SP) are required to be used in spintronic devices. The HM character has been predicted theoretically in many Heusler alloys thin films and confirmed by experiments. Full-Heusler alloy TiFeSn has been studied extensively. It has been reported that their (001)-oriented thin films with TiFe or TiSn terminations preserve 100% SP, but the HM character is unstable because the edge of the bandgap is closed to the Fermi level. Therefore, we investigate the effects of the Co-doping on the structural, electronic and magnetic properties of the bulk full-Heusler alloys TiFeCoSn (= 0.00, 0.25, 0.50, 0.75 or 1.00) and their (001)-oriented thin films. The bulk TiFeCoSn (= 0.00, 0.25, 0.50, 0.75 or 1.00) alloys are all HM ferromagnets. We investigate twelve possible terminations and show that five of them preserve HM character with 100% SP at the Fermi level, while in the remaining seven, surface states emerge in the spin-down channel at the Fermi level, significantly reducing their SP. The Co-doping significantly increases the stability of the TiSn slab, also increases its spin-down bandgapEg↓and HM gapEgHMat= 0.50. The stable HM character makes it is a slab of maximum benefit in the applications of spintronic devices, especially in magnetic tunnel junctions.
自旋电子器件需要使用具有稳定半金属（HM）特性和100%自旋极化（SP）的薄膜。理论上已预测许多赫斯勒合金薄膜具有HM特性，并通过实验得到证实。全赫斯勒合金TiFeSn已得到广泛研究。据报道，其具有TiFe或TiSn终端的（001）取向薄膜保持100%的SP，但HM特性不稳定，因为带隙边缘接近费米能级。因此，我们研究了Co掺杂对块状全赫斯勒合金TiFeCoSn（= 0.00、0.25、0.50、0.75或1.00）及其（001）取向薄膜的结构、电子和磁性的影响。块状TiFeCoSn（= 0.00、0.25、0.50、0.75或1.00）合金均为HM铁磁体。我们研究了12种可能的终端，并表明其中5种在费米能级保持具有100%SP的HM特性，而在其余7种中，在费米能级的自旋向下通道中出现表面态，显著降低了它们的SP。Co掺杂显著提高了TiSn平板的稳定性，还增加了其自旋向下带隙Eg↓和HM间隙EgHM，在x = 0.50时。稳定的HM特性使其成为自旋电子器件应用中最有益的平板，尤其是在磁性隧道结中。
