Spin-orbit coupling in fluorinated graphene
Spin-orbit coupling in fluorinated graphene
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DOI：
10.1103/physrevb.91.115141
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发表时间：
2014-10
影响因子：
3.7
通讯作者：
Susanne Irmer;T. Frank;S. Putz;M. Gmitra;D. Kochan;J. Fabian
中科院分区：
文献类型：
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作者：
Susanne Irmer;T. Frank;S. Putz;M. Gmitra;D. Kochan;J. Fabian
我们报告了氟化石墨烯中自旋轨道耦合效应的理论研究。针对稠密和稀吸附原子覆盖极限进行第一原理密度泛函计算。致密极限由单侧半氟化石墨烯代表，它是一种自旋轨道分裂约为 10 meV 的金属。为了模拟单个吸附原子的影响，我们还计算了 $10\ifmmode\times\else\texttimes\fi{}10$ 超晶胞的电子结构，其中一个氟原子位于顶部位置。由于该稀释极限对于研究自旋输运和自旋弛豫很有用，因此我们还基于对称性考虑引入了现实的有效跳跃哈密顿量，它描述了费米能级周围的超晶胞能带。我们提供最适合第一原理数据的哈密顿参数。我们证明，与氢吸附原子的情况不同，氟自身的自旋轨道耦合是石墨烯中巨诱导局部自旋轨道耦合的主要原因。 $s{p}^{3}$杂化诱导石墨烯的$\ensuremath{\sigma}$键的自旋轨道耦合转移，这对氢化石墨烯很重要，但贡献要小得多。此外，由于氟吸附原子引起的自旋轨道耦合的大小大约是原始石墨烯的1000倍，是氢化石墨烯的10倍。与氢不同的是，氟吸附原子在狄拉克点不是窄共振散射体。稀极限氟化石墨烯态密度的共振峰位于狄拉克点以下 260 meV。峰相当宽，约为 300 meV，使得氟吸附原子仅是弱共振散射体。
We report on theoretical investigations of the spin-orbit coupling effects in fluorinated graphene. First-principles density functional calculations are performed for the dense and dilute adatom coverage limits. The dense limit is represented by the single-side semifluorinated graphene, which is a metal with spin-orbit splittings of about 10 meV. To simulate the effects of a single adatom, we also calculate the electronic structure of a $10\ifmmode\times\else\texttimes\fi{}10$ supercell, with one fluorine atom in the top position. Since this dilute limit is useful to study spin transport and spin relaxation, we also introduce a realistic effective hopping Hamiltonian, based on symmetry considerations, which describes the supercell bands around the Fermi level. We provide the Hamiltonian parameters which are best fits to the first-principles data. We demonstrate that, unlike for the case of hydrogen adatoms, fluorine's own spin-orbit coupling is the principal cause of the giant induced local spin-orbit coupling in graphene. The $s{p}^{3}$ hybridization induced transfer of spin-orbit coupling from graphene's $\ensuremath{\sigma}$ bonds, important for hydrogenated graphene, contributes much less. Furthermore, the magnitude of the induced spin-orbit coupling due to fluorine adatoms is about 1000 times more than that of pristine graphene, and 10 times more than that of hydrogenated graphene. Also unlike hydrogen, the fluorine adatom is not a narrow resonant scatterer at the Dirac point. The resonant peak in the density of states of fluorinated graphene in the dilute limit lies 260 meV below the Dirac point. The peak is rather broad, about 300 meV, making the fluorine adatom only a weakly resonant scatterer.