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arXiv 2108.06012cond-mat.supr-con
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超导体PbTaSe2中观测到的抗磁性杂质的鲁棒拓扑态

Robust topological state against magnetic impurities observed in superconductor PbTaSe2

Daniel Multer, Jia-Xin Yin, Songtian S. Zhang, Hao Zheng, Tay-Rong Chang, Guang Bian, Raman Sankar, M. Zahid Hasan

摘要:

沉积在拓扑超导体候选物PbTaSe 2上的磁性杂质可以在超导能隙内引入非分裂零能态,这被认为是拓扑零模的无场平台。然而,目前还不清楚PbTaSe 2中的拓扑状态对磁性杂质的鲁棒性如何,这与零能态的拓扑性质及其量子计算潜力有关。本文利用扫描隧道显微镜(STM)研究了PbTaSe_2正常态在磁性杂质微扰下的表面拓扑态。我们可视化的准粒子干涉(QPI)所产生的拓扑表面状态。然后,我们在表面上沉积Fe杂质以形成原子Fe吸附原子。我们发现每个Fe吸附原子位于表面上的一个独特的间隙位置,并在高能量下具有局域态,这两者都与我们的第一性原理计算一致,进一步揭示了其大的磁矩。我们的系统的Fe沉积和随后的测量表明,在费米能量的弧形QPI图案是强大的Fe覆盖率高达3%,其中Fe吸附原子的原子性质仍然保持。我们的研究结果提供的证据表明,拓扑表面状态在费米能级PbTaSe 2是强大的对稀磁杂质。

英文摘要:

Magnetic impurities deposited on topological superconductor candidate PbTaSe2 can introduce a non-splitting zero-energy state inside the superconducting gap, which has been proposed as a field-free platform for topological zero modes. However, it is still unclear how robust the topological state in PbTaSe2 is against magnetic impurities, which is related to the topological nature of the zero-energy state as well as its potential for quantum computation. In this work, we use scanning tunneling microscopy (STM) to study the topological surface state in the normal state of PbTaSe2 under the perturbation of magnetic impurities. We visualize the quasi-particle interference (QPI) arising from the topological surface state. We then deposit Fe impurities on the surface to form atomic Fe adatoms. We find that each Fe adatom sits at a unique interstitial position on the surface and features a local state at high energies, both of which are consistent with our first-principles calculation that further reveals its large magnetic moment. Our systematic Fe deposition and subsequent measurements show that the arc-like QPI pattern at the Fermi energy is robust with up to 3% Fe coverage where the atomic nature of Fe adatoms still holds. Our results provide evidence that the topological surface state at the Fermi energy in PbTaSe2 is robust against dilute magnetic impurities.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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