International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, Aleja Lotnikow 32/46, PL-02668 Warsaw, Poland.
Department of Applied Physics, Aalto University, 00076 Aalto, Espoo, Finland.
Phys Rev Lett. 2023 Jun 9;130(23):237002. doi: 10.1103/PhysRevLett.130.237002.
Semiconducting nanowires with strong spin-orbit coupling in the presence of induced superconductivity and ferromagnetism can support Majorana zero modes. We study the pumping due to the precession of the magnetization in single-subband nanowires and show that spin pumping is robustly quantized when the hybrid nanowire is in the topologically nontrivial phase, whereas charge pumping is not quantized. Moreover, there exists one-to-one correspondence between the quantized conductance, entropy change and spin pumping in long topologically nontrivial nanowires but these observables are uncorrelated in the case of accidental zero-energy Andreev bound states in the trivial phase. Thus, we conclude that observation of correlated and quantized peaks in the conductance, entropy change and spin pumping would provide strong evidence of Majorana zero modes, and we elaborate how topological Majorana zero modes can be distinguished from quasi-Majorana modes potentially created by a smooth tunnel barrier at the lead-nanowire interface. Finally, we discuss peculiar interference effects affecting the spin pumping in short nanowires at very low energies.
在诱导超导和铁磁共存的情况下，具有强自旋轨道耦合的半导体纳米线可以支持马约拉纳零模。我们研究了单亚带纳米线中磁化进动引起的泵送，并表明当混合纳米线处于拓扑非平凡相时，自旋泵送是稳健的量子化，而电荷泵送不是量子化的。此外，在长拓扑非平凡纳米线中，量子化电导、熵变和自旋泵送之间存在一一对应关系，但在平凡相中偶然出现的零能安德烈夫束缚态情况下，这些可观测量是不相关的。因此，我们得出结论，观察电导、熵变和自旋泵送中的相关和量化峰值将为马约拉纳零模提供强有力的证据，我们详细说明了如何区分拓扑马约拉纳零模和可能由引线-纳米线界面处平滑隧道势垒产生的准马约拉纳模。最后，我们讨论了影响短纳米线中极低能量自旋泵送的特殊干涉效应。
