论文标题
激光启用的Fe $ _ {1} $/（MGO）$ _ {3} $（001）异构结构的各向异性载体动力学
Anisotropic carrier dynamics in a laser-excited Fe$_{1}$/(MgO)$_{3}$(001) heterostructure from real-time time-dependent DFT
论文作者
论文摘要
飞秒光脉冲与Fe $ _ {1} $/（mgo）$ _ {3} $（001）金属/氧化物异质结构的相互作用是使用实时域中的时间依赖性密度功能理论（TDDFT）计算研究的。我们系统地研究电子激发，这是激光频率，峰值功率密度和极化方向的函数。虽然发现自旋轨道耦合仅导致磁化磁化的较小降低（少于10％），但我们发现在对面内和平面偏光范围的响应中，明显的各向异性在响应中，这是在低于频率上有效地在低频上散发出较高的频率的频率，从而改变其特征，从而改变其性能，而不是频繁的光，并且在平面偏光范围内，以及范围更高的频率，以及范围的偏光范围，以及多个频率的仪式，以及范围的光线，以及多边形的范围，以及范围的偏光范围。我们发现中央MGO层对于跨平面极化光特别强烈。对于电荷传输差距和MGO频段间隙之间的激光激发，该界面起着最重要的作用，因为它将从MGO价值带介导了Fermi水平高于Fermi级别的FE状态的$ 3D $状态，并将Fermi级别以下的FE-States的$ 3D $状态介导了MGO的频率。由于这些过渡可以同时改变层的电荷平衡，因此它们可能会导致激发载体有效地转移到MGO批量上，在那里，相应的电子和孔状态可以通过明显大于光子能量大的能量分离。
The interaction of a femtosecond optical pulse with a Fe$_{1}$/(MgO)$_{3}$(001) metal/oxide heterostructure is investigated using time-dependent density functional theory (TDDFT) calculations in the real-time domain. We systematically study electronic excitations as a function of laser frequency, peak power density and polarization direction. While spin-orbit coupling is found to result in only a small time-dependent reduction of magnetization (less than 10%), we find a marked anisotropy in the response to in-plane and out-of-plane polarized light, which changes its character qualitatively depending on the excitation energy: the Fe-layer is efficiently addressed at low frequencies by in-plane polarized light, whereas for frequencies higher than the MgO band gap, we find a particularly strong response of the central MgO-layer for cross-plane polarized light. For laser excitations between the charge transfer gap and the MgO band gap, the interface plays the most important role, as it mediates concerted transitions from the valence band of MgO into the $3d$ states of Fe closely above the Fermi level and from the Fe-states below the Fermi level into the conduction band of MgO. As these transitions can occur simultaneously altering charge balance of the layers, they could potentially lead to an efficient transfer of excited carriers into the MgO bulk, where the corresponding electron and hole states can be separated by an energy which is significantly larger than the photon energy.
