论文标题
原子级螺旋磁铁中的电荷和自旋泵送理论
Theory of charge and spin pumping in atomic-scale spiral magnets
论文作者
论文摘要
Archimedean螺钉是一个经典的泵，可利用旋转和螺旋中的翻译等效性。同样，旋转螺旋纹理可以通过以频率$ω$旋转来泵送电荷和旋转。在本文中，我们通过扰动理论和数值模拟研究了微观量子模型中的这些泵种现象。在螺旋区域内，自旋极化和电荷电流为$ω$，而旋转电流为$ω^2 $对于小$ω$。我们发现电荷电流与混合动量浆果相有关，该相位可以看作是无与伦比的泵的新型近似实现。它几乎是在短音调$λ$的螺旋中量化的，但与$λ^{ - 1} $腐烂了更长的音高，这与真实的泵或阿基梅德螺钉不同。此外，我们研究了非绝热性（大$ω$）的发作，附着的非磁性或磁性接触的影响以及传输可观察物的实时演变。最后，我们分析了疾病的影响，令人惊讶的是，这些疾病可能会增强自旋电流，但会抑制电荷电流。
An Archimedean screw is a classical pump that exploits the equivalence of rotation and translation in helices. Similarly, a spin spiral texture can pump charge and spin by rotating at a frequency $ω$. In the present paper, we study these pumping phenomena within a microscopic quantum model by both perturbation theory and numerical simulations. Inside the spiral region, the spin polarization and charge current are linear in $ω$ whereas the spin current is $ω^2$ for small $ω$. We find that the charge current is related to the mixed momentum-phason Berry phase, which can be viewed as a novel approximate realization of a Thouless pump. It is nearly quantized in spirals with short pitch $λ$ but decays with $λ^{-1}$ for longer pitches, unlike true Thouless pumps or Archimedian screws. Moreover, we study the onset of non-adiabaticity (large $ω$), the impact of attached non-magnetic or magnetic contacts, and the real-time evolution of the transport observables. Finally, we analyze the effects of disorders which, surprisingly, might enhance the spin current but suppress the charge current.
