论文标题
磁性材料注射光电流的内在效率
Intrinsic efficiency of injection photocurrents in magnetic materials
论文作者
论文摘要
非中心对称材料中的移位和弹道光电的产生代表了轻能收集的有希望的替代机制。许多研究的重点是通过最大化光电流幅度来找到最适合的材料，但是估算实际效率需要了解光引起的直流光电导率，并且很少考虑。在这项工作中，使用最近提出的混蛋电流作为光电导率，只有弹道光电在大松弛时间$τ$的极限下具有有限的效率。此外，在零温度下，唯一有限的弹道电流是磁性注射电流，仅在磁性材料中存在。我们提出了这种光电流效率的频带结构表达式，表明它比带边缘附近的$（\ hbarω-e_g）^2 $缩放为$（\ hbarω-e_g）^2 $，我们为简单的紧密结合模型提供了其频率依赖性。我们的工作提供了一种新工具，可以根据磁注入电流指导搜索有效的能量收集。
The generation of shift and ballistic photocurrents in non-centrosymmetric materials represents a promising alternative mechanism for light energy harvesting. Many studies have focused on finding the best suited materials by maximizing the photocurrent magnitude, but estimating the actual efficiency requires knowledge of the light-induced DC photoconductivity and is rarely considered. Using the recently proposed jerk current as photoconductivity, in this work we show that only ballistic photocurrents have finite efficiency in the limit of large relaxation times $τ$. Moreover, at zero temperature the only ballistic current which is finite for unpolarized light is the magnetic injection current, only present in magnetic materials. We present a band structure expression for the efficiency of such photocurrent, showing that it scales as $(\hbar Ω-E_g)^2$ near the band edge, and we present its frequency dependence for a simple tight-binding model. Our work provides a new tool to guide the search for efficient energy harvesting based on the magnetic injection current.
