Fu Yan-Long, Zhang Zhao-Jun, Li Chang-Kai, Sang Hai-Bo, Cheng Wei, Zhang Feng-Shou
The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, People's Republic of China. Beijing Radiation Center, Beijing 100875, People's Republic of China.
J Phys Condens Matter. 2020 Mar 6;32(10):105701. doi: 10.1088/1361-648X/ab598c. Epub 2019 Nov 20.
The electronic stopping power for low-velocity ions (including protons, [Formula: see text]-particles, and [Formula: see text]) is investigated in a novel semimetal HgTe system, where the data are obtained with the aid of Ehrenfest dynamics combined with time-dependent density functional theory. For the light projectile ions (protons and [Formula: see text]-particles), the linear and nonlinear behaviors of electronic stopping power in three different channel directions are analyzed in detail. In the case where the projectile ion is a proton, the linear results for the threshold velocity are correlated with an indirect band gap; the direction of the electronic stopping power depends on the radial drag force, the channeling electronic density and the trapped charge. More notably, we report an interesting channel-geometry fact, i.e. that the electronic stopping power of HgTe is powerfully modulated by the impact parameters. The parallel off-center tracks increase the electronic stopping power, making it more consistent with the SRIM data. In the case of an [Formula: see text]-particle as the projectile ion, nonlinear behavior that varies with velocity can be ascribed to the charge transfer, which is another mode of energy dissipation. In addition, when the slightly heavier projectile [Formula: see text] travels through the medium HgTe, the projectile [Formula: see text] can capture more free charges than the protons and [Formula: see text]-particles under the same circumstances. Especially, for the projectile in the off-channel, the electronic stopping power is close to the SRIM data with the decrease of the impact parameter. These results extend the study of radiation damage to a new field of materials.
在一种新型半金属HgTe系统中研究了低速离子（包括质子、α粒子和μ子）的电子阻止本领，其中借助埃伦费斯特动力学结合含时密度泛函理论获得数据。对于轻入射离子（质子和α粒子），详细分析了在三个不同沟道方向上电子阻止本领的线性和非线性行为。当入射离子为质子时，阈值速度的线性结果与间接带隙相关；电子阻止本领的方向取决于径向拖曳力、沟道电子密度和俘获电荷。更值得注意的是，我们报道了一个有趣的沟道几何事实，即HgTe的电子阻止本领受到碰撞参数的强烈调制。平行偏心轨迹增加了电子阻止本领，使其更符合SRIM数据。当α粒子作为入射离子时，随速度变化的非线性行为可归因于电荷转移，这是另一种能量耗散模式。此外，当稍重的入射粒子μ子穿过介质HgTe时，在相同情况下，入射粒子μ子比质子和α粒子能俘获更多的自由电荷。特别是，对于非沟道中的入射粒子，随着碰撞参数的减小，电子阻止本领接近SRIM数据。这些结果将辐射损伤的研究扩展到了材料的一个新领域。
