论文标题
旋转和电荷泵送的量子古典方法以及THZ Spintronics中随后的辐射：超轻型驱动的Weyl抗fiferromagnet Mn $ _3 $ sn
Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics: Example of ultrafast-light-driven Weyl antiferromagnet Mn$_3$Sn
论文作者
论文摘要
FS光脉冲与磁性材料的相互作用已经深入研究了二十多年，以便了解单磁层中的超快消极磁化或使用非磁性自旋轨道（SO）材料的双层发射的THZ发射。在这里，我们开发了一种多尺度量子古典形式主义 - 其中传导电子由lindblad类型的量子主方程描述； Landau-Lifshitz-Gilbert（LLG）方程描述了局部磁化的经典动力学；传入的光是经典矢量电位描述的，而外向电磁辐射则使用Jefimenko方程计算出智障的电场和磁场 - 并将其应用为反铁磁性WEYL半磁性Mn $ _3 $ _3 $ _3 $ _3 $ sn的双层，并与非授粉的局部磁力化在与该互联面的非磁性材料接触中进行非胶结磁力化。我们的QME+LLG+Jefimenko方案使得FS Light Pulse如何通过后者直接生成旋转和充电泵送和电磁辐射，包括奇数甚至高谐波（脉冲中心频率），以达到$ n \ le 7 $。直接泵送的自旋电流然后在局部磁化强度上施加自旋扭矩，而动力学又在THZ范围内泵送了额外的自旋和电荷电流。通过打开和关闭LLG动力学以及如此的耦合，我们揭示了哪种微观机制最大程度地促进了发射的辐射 - 在其固有的情况下，通过局部磁化的局部磁化来泵送，因此耦合的存在，因此耦合比标准型（对于其他类型的磁性层次旋转）旋转旋转和随后的旋转和随后的旋转和随后的旋转旋转和随后的旋转，并进行了进一步的旋转。
The interaction of fs light pulses with magnetic materials has been intensely studied for more than two decades in order to understand ultrafast demagnetization in single magnetic layers or THz emission from their bilayers with nonmagnetic spin-orbit (SO) materials. Here we develop a multiscale quantum-classical formalism -- where conduction electrons are described by quantum master equation of the Lindblad type; classical dynamics of local magnetization is described by the Landau-Lifshitz-Gilbert (LLG) equation; and incoming light is described by classical vector potential while outgoing electromagnetic radiation is computed using Jefimenko equations for retarded electric and magnetic fields -- and apply it a bilayer of antiferromagnetic Weyl semimetal Mn$_3$Sn with noncollinear local magnetization in contact with SO-coupled nonmagnetic material. Our QME+LLG+Jefimenko scheme makes it possible to understand how fs light pulse generates directly spin and charge pumping and electromagnetic radiation by the latter, including both odd and even high harmonics (of the pulse center frequency) up to order $n \le 7$. The directly pumped spin current then exert spin torque on local magnetization whose dynamics, in turn, pumps additional spin and charge currents radiating in the THz range. By switching on and off LLG dynamics and SO couplings, we unravel which microscopic mechanism contribute the most to emitted THz radiation -- charge pumping by local magnetization of Mn$_3$Sn in the presence of its intrinsic SO coupling is far more important than standardly assumed (for other types of magnetic layers) spin pumping and subsequent spin-to-charge conversion within the neighboring nonmagnetic SO-coupled material.
