A new Majorana platform in an Fe-As bilayer superconductor

Abstract

Recently, iron-chalcogenide superconductors have emerged as a new and promising platform for studying and manipulating Majorana zero mode (MZM). By combining topological band structure and superconductivity in a multiband material, they provide significant advantages such as higher superconducting transition temperature (Tc) and isolated Majorana mode. However, iron-chalcogenide superconductors, especially Fe(Te,Se), suffer from strong inhomogeneity which may hamper their practical application. On the other hand, some iron-pnictide (Fe-As) superconductors, such as LiFeAs, have been demonstrated to have a similar topological band structure, yet no MZM has been observed in its vortex cores, raising a question of universality of MZM presence in iron-based superconductors. In this work, by using high-resolution angle-resolved photoemission spectroscopy and scanning tunneling microscopy/spectroscopy, we identify the first Fe-As superconductor CaKFe4As4 (Tc = 35 K) which has both the superconducting Dirac surface states and the MZMs inside its vortex cores. The topological band inversion is largely due to the down-shift of the pz band caused by the bilayer band folding in this material. More strikingly, the energies and spatial line profiles of MZM and multiple quantized Caroli-de Gennes-Matricon bound states observed inside the topological vortex can be accurately reproduced by a simple theoretical model derived from a surface Dirac cone, firmly establishing Majorana nature of the zero mode.

References in corpus (24)

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• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Unpaired Majorana fermions in quantum wires
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• Paired states of fermions in two dimensions with breaking of parity and time-reversal symmetries, and the fractional quantum Hall effect
• New directions in the pursuit of Majorana fermions in solid state systems
• Evidence for Majorana bound state in an iron-based superconductor
• Observation of topological superconductivity on the surface of an iron-based superconductor
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• A precise method for visualizing dispersive features in image plots
• Zero-energy vortex bound state in the superconducting topological surface state of Fe(Se,Te)
• Multiple topological states in iron-based superconductors
• Observation of half-integer level shift of vortex bound states in an iron-based superconductor
• Low-lying Quasiparticle Excitations around a Vortex Core in Quantum Limit
• Discrete energy levels of Caroli-de Gennes-Martricon states in quantum limit due to small Fermi energy in FeTe${}_{0.55}$Se${}_{0.45}$
• Optimization of the Crystal Growth of the Superconductor CaKFe${}_4$As${}_4$ from Solution in the FeAs-CaFe${}_2$As${}_2$-KFe${}_2$As${}_2$ System
• Evolution of density of states and spin-resolved "checkerboard" pattern associated with Majorana bound state
• Nodeless multiband superconductivity in stoichiometric single crystalline CaKFe${}_4$As${}_4$
• Influence of the multiband sign changing superconductivity on the vortex cores and on vortex pinning in the new stoichiometric high Tc CaKFe4As4
• ARPES measurements of the superconducting gap of Fe-based superconductors and their implications to the pairing mechanism
• Atomic and electronic structures of ternary iron arsenides $A$Fe${}_2$As${}_2$(001) surfaces ($A$=Ba, Sr, or Ca)
• Electronic properties, low-energy Hamiltonian and superconducting instabilities in CaKFe${}_4$As${}_4$
• Vorticity and vortex-core states
• Decoupled Pairing Amplitude and Electronic Coherence in Iron-Based Superconductors

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• Intrinsic Time-reversal-invariant Topological Superconductivity in Thin Films of Iron-based Superconductors
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• Helical Liquids in Semiconductors
• Friedel Oscillations of Vortex Bound States Under Extreme Quantum Limit in KCa2Fe4As4F2
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• Phase-manipulation-induced Majorana Mode and Braiding Realization in Iron-based Superconductor Fe(Te,Se)
• Tunable vortex Majorana modes controlled by strain in homogeneous LiFeAs
• Correlation-corrected band topology and topological surface states in iron-based superconductors
• Topological Superconducting Vortex From Trivial Electronic Bands
• Family of binary transition metal pnictide superconductors
• Optimizing the transport of Majorana zero modes in one-dimensional topological superconductors
• Topological superconductivity and large spin Hall effect in the kagome family Ti6X4 (X = Bi, Sb, Pb, Tl, In)
• Quarter-quantized thermal Hall effect with parity anomaly
• Differential current noise as an identifier of Andreev bound states that induce nearly quantized conductance plateaus
• Meissner effect induced Majorana zero modes at small magnetic field
• Prediction of Double-Weyl Points in the Iron-Based Superconductor CaKFe${}_4$As${}_4$
• Searching for Majorana quasiparticles at vortex cores in iron-based superconductors
• Unveiling non-Abelian statistics of vortex Majorana bound states in iron-based superconductors using fermionic modes
• Identifying Majorana vortex modes via non-local transport
• Stoichiometric FeTe is a Superconductor
• Topological properties of non-centrosymmetric superconductors $T$Ir${}_2$B${}_2$ ($T$=Nb, Ta)
• Anomalous Coherence Length of Majorana Zero Modes at Vortices in Superconducting Topological Insulators
• Anomalous metallic oxygen band in the potential superconductor KCa${}_2$Fe${}_4$As${}_4$O${}_2$
• Controllable Majorana vortex states in iron-based superconducting nanowires
• Proximity-induced zero-energy states indistinguishable from topological edge states
• Visualization of Unconventional Rashba Band and Vortex Zero Mode in Topopogical Superconductor Candidate AuSn${}_4$
• Theoretical proposal to obtain strong Majorana evidence from scanning tunneling spectroscopy of a vortex with a dissipative environment
• Interlayer magnetic interactions and ferroelectricity in $\pi$/3-twisted CrX${}_2$ (X = Se, Te) bilayers
• Superconductivity and vortex structure on Bi${}_2$Te${}_3$/FeTe${}_{0.55}$Se${}_{0.45}$ heterostructures with different thickness of Bi${}_2$Te${}_3$ films
• Necklace-like pattern of vortex bound states
• Large spectral gap and impurity-induced states in a two-dimensional Abrikosov vortex
• Zero-energy modes, fractional fermion numbers and the index theorem in a vortex-Dirac fermion system
• Helical Topological Superconducting Pairing at Finite Excitation Energies
• Angular momentum of vortex-core Majorana zero modes
• Deterministic topological quantum gates for Majorana qubits without ancillary modes
• Superconductor Vortex Spectrum Including Fermi Arc States in Time-Reversal Symmetric Weyl Semimetals
• Magnetic-field driven evolution of zero-energy mode on Bi islands deposited on Fe(Te,Se)
• Linear scaling relation between two-dimensional massless Dirac fermion Fermi velocity and Fe-As bond length in iron arsenide superconductor systems
• Dissipationless topological quantum computation for Majorana objects in sparse-dense mixed encoding process
• Fe${}_{1+y}$Te${}_x$Se${}_{1-x}$: a delicate and tunable Majorana material
• Anisotropic superconductivity and Fermi surface reconstruction in the spin-vortex antiferromagnetic superconductor CaK(Fe${}_{0.95}$Ni${}_{0.05}$)${}_4$As${}_4$
• Phase diagrams of superconducting topological surface states
• Nontrivial topological states in BaSn5 superconductor probed by de Haas-van Alphen quantum oscillations
• First-principles study of the electronic structure of CaKRu${}_4$P${}_4$
• Intrinsic chiral topological superconductor thin films
• A mesoscopic device for a realization of the Topological Kondo effect
• Unveiling In-Gap States and Majorana Zero Modes in Superconductor-Topological Insulator Bilayer model
• Evolution of the intertwining correlated topological phases in iron-based superconductor Fe(Te,Se)
• Efficient slave-boson approach for multiorbital two-particle response functions and superconductivity
• Superconductivity in the pressure-amorphized topological insulator CrP${}_4$
• Binary kagome superconducting candidates hosting topological electronic states
• Vortex creation and control in the Kitaev spin liquid by local bond modulations