A new Majorana platform in an Fe-As bilayer superconductor

Liu, Wenyao; Cao, Lu; Zhu, Shiyu; Kong, Ling-Yuan; Wang, Guangwei; Papaj, Michał; Zhang, Peng; Liu, Ya-Bin; Chen, Hui; Li, Geng; Yang, Fuhan; Kondo, Takeshi; Du, Shixuan; Cao, Guang‐Han; Shin, Shik; Fu, Liang; Yin, Zhiping; Gao, Hongjun; Ding, Hong

doi:10.1038/s41467-020-19487-1

Cited by 115 publications

(81 citation statements)

References 35 publications

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“…These fundamental properties, previously unobserved in superconductors, are consistent with the predications of the theoretical proposal of the QAV 28 . They have broad implications for superconductors with a nontrivial topological band structure and spin-momentum locked superconducting TSS, which have also been found in several other iron-based superconductors such as LiFeAs 35,36 , (Li 0.84 Fe 0.16 )OHFeSe 37 , and CaKFe 4 As 4 38 . We also noticed a recent preprint posted on the arxiv 39 , where the result shows absence of spin-polarization on a ZBP.…”

Section: Discussionmentioning

confidence: 84%

Observation of magnetic adatom-induced Majorana vortex and its hybridization with field-induced Majorana vortex in an iron-based superconductor

et al. 2021

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Braiding Majorana zero modes is essential for fault-tolerant topological quantum computing. Iron-based superconductors with nontrivial band topology have recently emerged as a surprisingly promising platform for creating distinct Majorana zero modes in magnetic vortices in a single material and at relatively high temperatures. The magnetic field-induced Abrikosov vortex lattice makes it difficult to braid a set of Majorana zero modes or to study the coupling of a Majorana doublet due to overlapping wave functions. Here we report the observation of the proposed quantum anomalous vortex with integer quantized vortex core states and the Majorana zero mode induced by magnetic Fe adatoms deposited on the surface. We observe its hybridization with a nearby field-induced Majorana vortex in iron-based superconductor FeTe0.55Se0.45. We also observe vortex-free Yu-Shiba-Rusinov bound states at the Fe adatoms with a weaker coupling to the substrate, and discover a reversible transition between Yu-Shiba-Rusinov states and Majorana zero mode by manipulating the exchange coupling strength. The dual origin of the Majorana zero modes, from magnetic adatoms and external magnetic field, provides a new single-material platform for studying their interactions and braiding in superconductors bearing topological band structures.

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Section: Discussionmentioning

confidence: 84%

Observation of magnetic adatom-induced Majorana vortex and its hybridization with field-induced Majorana vortex in an iron-based superconductor

et al. 2021

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“…Topological band structure has been found to be universal in iron-based superconductors [101]. Vortex MZMs were observed in (Li,Fe)OHFeSe [273,274] and CaKFe 4 As 4 [106]; 4) exploration of new compounds of iron-based superconductors which may support vortex MZM at higher temperatures. Experimental studies identified a topological band structure in a high-T c superconductor Fe(Te,Se) monolayer [267,268], indicating that the monolayer of iron-based superconductor may be a high-temperature Majorana platform above the liquid helium temperature [75].…”

Section: Discussionmentioning

confidence: 99%

“…By implementing the wavefunction and angular momentum analysis, we derived some conclusions of the influence of Dirac surface states on the vortex bound states, as listed below: 1) reversing the direction of magnetic field changes the sign of vorticity, consequently changing the positive and negative correspondence between ν and E ν , but it does not change the sign of the energy of the second solid-circle-pattern level [106]; 2) the sign of the chemical potential determines the sign of the energy of the second solid-circle-pattern level. Specifically, the second solid-circle-pattern level appears in the unoccupied side (positive energy) when µ > 0, and vice versa; 3) at the vortex center, the spin of the zero-energy level is always parallel to the magnetic field, while the spin of the second solid-circle-pattern level is always anti-parallel to the magnetic field.…”

Section: A Vortex Bound State With Topologymentioning

confidence: 99%

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Emergent vortex Majorana zero mode in iron-based superconductors

Kong¹,

Ding²

2020

Acta Phys. Sin.

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The vortex of iron-based superconductors is emerging as a promising platform for Majorana zero mode, owing to a magic integration among intrinsic vortex winding, non-trivial band topology, strong electron-electron correlations, high-Tc superconductivity and the simplification of single material. It overcomes many difficulties suffered in heterostructure-based Majorana platforms, including small topological gap, interfacial contamination, lattice imperfections, and etc. Isolated zero-bias peaks have been found in vortex of several iron-based superconductors. So far, studies from both experimental and theoretical aspects strongly indicate the realization of vortex Majorana zero mode, with a potential to be applied to fault-tolerant quantum computation. By taking Fe(Te,Se) superconductor as an example, here we review the original idea and research progress of Majorana zero modes in this new platform. After introducing the identifications of topological band structure and real zero modes in vortex, we summarize the physics behaviors of vortex Majorana zero modes systematically. First, relying on the behavior of the zero mode wave function and evidence of quasiparticle poisoning, we analyze the mechanism of emergence of vortex Majorana zero modes. Secondly, assisted with some well-established theories, we elaborate the measurements on "Majorana symmetry" and topological nature of vortex Majorana zero modes. After that, we switch from quantum physics to quantum engineering, and analyze the performance of vortex Majorana zero modes under real circumstances, which may potentially benefit the exploration of practical applications in the future. This review follows the physics properties of vortex Majorana zero modes, especially emphasizes the link between phenomena and mechanisms. It provides a chance to bridge the gap between the well-established theories and the newly discovered "iron home" of Majoranas.

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“…Furthermore, a VUV laser light source with a photon energy range of 5.9-7 eV is utilized in this endstation to improve the ARPES performance. This endstation is open to users and has enabled the discovery of many important materials, such as the bilayer superconductor Fe-As [21], magnetic Weyl semimetal Co 3 Sn 2 S 2 [22], magnetic topological insulator MnBi 2 Te 4 [23][24][25], and topological nodal-line semimetal SrAs 3 [26].…”

Section: Introductionmentioning

confidence: 99%

High-resolution ARPES endstation for in situ electronic structure investigations at SSRF

Yang

Liu

et al. 2021

NUCL SCI TECH

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Angle-resolved photoemission spectroscopy (ARPES) is one of the most powerful experimental techniques in condensed matter physics. Synchrotron ARPES, which uses photons with high flux and continuously tunable energy, has become particularly important. However, an excellent synchrotron ARPES system must have features such as a small beam spot, super-high energy resolution, and a user-friendly operation interface. A synchrotron beamline and an endstation (BL03U) were designed and constructed at the Shanghai Synchrotron Radiation Facility. The beam spot size at the sample position is 7.5 (V) lm 9 67 (H) lm, and the fundamental photon range is 7-165 eV; the ARPES system enables photoemission with an energy resolution of 2.67 meV at 21.2 eV. In addition, the ARPES system of this endstation is equipped with a six-axis cryogenic sample manipulator (the lowest temperature is 7 K) and is integrated with an oxide molecular beam epitaxy system and a scanning tunneling microscope, which can provide an advanced platform for in situ characterization of the fine electronic structure of condensed matter.

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A new Majorana platform in an Fe-As bilayer superconductor

Cited by 115 publications

References 35 publications

Observation of magnetic adatom-induced Majorana vortex and its hybridization with field-induced Majorana vortex in an iron-based superconductor

Observation of magnetic adatom-induced Majorana vortex and its hybridization with field-induced Majorana vortex in an iron-based superconductor

Emergent vortex Majorana zero mode in iron-based superconductors

High-resolution ARPES endstation for in situ electronic structure investigations at SSRF

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