Induced superconducting correlations in the quantum anomalous Hall insulator

Abstract

Inducing Cooper pairing in a thin ferromagnetic topological insulator in the quantum anomalous Hall state (called quantum anomalous Hall insulator, QAHI) is a promising way to realize topological superconductivity with associated chiral Majorana edge states. However, finding evidence of superconducting proximity effect in a QAHI has proven to be a considerable challenge due to inherent experimental difficulties. Here we report the observation of crossed Andreev reflection (CAR) across a narrow superconducting Nb electrode contacting the chiral edge state of a QAHI, evinced by a negative nonlocal voltage measured downstream from the grounded Nb electrode. This is an unambiguous signature of induced superconducting pair correlation in the chiral edge state. Our theoretical analysis demonstrates that CAR processes of the chiral edge are not strongly dependent on the nature of the superconductivity that mediates them. Nevertheless, the characteristic length of the CAR process is found to be much longer than the superconducting correlation length in Nb, which suggests that the CAR is in fact mediated by superconductivity induced on the QAHI surface. The approach and results presented here provide a foundation for future studies of topological superconductivity and Majorana physics, as well as for the search for non-Abelian zero modes.

arXiv comment45 pages total; 27 pages of main text with 4 figures, 18 pages of supplement with 9 figures

References in corpus (50)

• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Kwant: a software package for quantum transport
• Josephson Current and Noise at a Superconductor-Quantum Spin Hall Insulator-Superconductor Junction
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Electrically detected interferometry of Majorana fermions in a topological insulator
• Probing Neutral Majorana Fermion Edge Modes with Charge Transport
• Chiral Topological Superconductor From the Quantum Hall State
• A Josephson junction supercurrent diode
• Exotic non-Abelian anyons from conventional fractional quantum Hall states
• $4\pi$-periodic Josephson supercurrent in HgTe-based topological Josephson junctions
• Induced Superconductivity in the Quantum Spin Hall Edge
• Universal topological quantum computation from a superconductor/Abelian quantum Hall heterostructure
• Topological phases with parafermions: theory and blueprints
• Coherent control of single electrons: a review of current progress
• Superconducting Proximity Effect on the Edge of Fractional Topological Insulators
• Chiral topological superconductor and half-integer conductance plateau from quantum anomalous Hall plateau transition
• Inducing Superconducting Correlation in Quantum Hall Edge States
• Fractional topological superconductors with fractionalized Majorana fermions
• Non-Majorana Origin of the Half-Quantized Conductance Plateau in Quantum Anomalous Hall Insulator and Superconductor Hybrid Structures
• Andreev Reflection in Strong Magnetic Fields
• Part-per-million quantization and current-induced breakdown of the quantum anomalous Hall effect
• Exotic circuit elements from zero-modes in hybrid superconductor/quantum Hall systems
• Deterministic creation and braiding of chiral edge vortices
• Interference of chiral Andreev edge states
• Andreev reflection in the fractional quantum Hall state
• Quasi-one-dimensional Quantum Anomalous Hall Systems as New Platforms for Scalable Topological Quantum Computation
• Anomalous Fraunhofer patterns in gated Josephson junctions based on the bulk-insulating topological insulator BiSbTeSe2
• Current-driven instability of quantum anomalous Hall effect in ferromagnetic topological insulators
• Crossed Andreev effects in two-dimensional quantum Hall systems
• Induced superconducting pairing in integer quantum Hall edge states
• Survival of the quantum anomalous Hall effect in orbital magnetic fields as a consequence of the parity anomaly
• Quantum anomalous Hall edge channels survive up to the Curie temperature
• Current-induced breakdown of the quantum anomalous Hall effect
• Confinement-Induced Chiral Edge Channel Interaction in Quantum Anomalous Hall Insulators
• Conductance oscillations with magnetic field of a two-dimensional electron gas-superconductor junction
• Disorder in Andreev reflection of a quantum Hall edge
• Superconductivity and fermionic dissipation in quantum Hall edges
• Andreev transport in two-dimensional normal-superconducting systems in strong magnetic fields
• Electrically tunable spin polarization of chiral edge modes in a quantum anomalous Hall insulator
• Mesoscopic Transport of Quantum Anomalous Hall Effect in Sub-Micron Size Regime
• Supercurrent-enabled Andreev reflection in a chiral quantum Hall edge state
• Bulk dissipation in the quantum anomalous Hall effect
• Upper critical field and superconductor-metal transition in ultrathin niobium films
• Nonlocal superconducting correlations in graphene in the quantum Hall regime
• Vortex-enabled Andreev processes in quantum Hall-superconductor hybrids
• Electrical detection of the Majorana fusion rule for chiral edge vortices in a topological superconductor
• Geometrical effects on the downstream conductance in quantum-Hall--superconductor hybrid systems
• Fate of Quantum Anomalous Hall Effect in the Presence of External Magnetic Fields and Particle-Hole Asymmetry
• Time-resolved electrical detection of chiral edge vortex braiding

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• On-Demand and Tunable Andreev-Conversion of Single-Electron Charge Pulses
• Thermal properties of the superconductor-quantum Hall interfaces
• Floquet-Nambu theory of electron quantum optics with superconductors
• Laughlin charge pumping from interplay of chiral Dirac and chiral Majorana modes
• Robust quantized thermal conductance of Majorana floating edge bands in d-wave superconductors
• Quasi-${\Phi }_0$-periodic supercurrent at quantum Hall transitions
• Edge optical effect as a probe of chiral topological superconductors
• Majorana fermion induced power-law scaling in the violations of the Wiedemann-Franz law
• Revealing Superconducting Chiral Edge Modes via Resistance Distributions
• Quantized Transport of $\nu =2/3$ Fractional Quantum Hall Edge with Disordered Superconducting Proximity
• Controlling the magneto-transport properties of magnetic topological insulator thin films from Cr${}_x$(Bi${}_y$Sb${}_{1-y}$)${}_{2-x}$Te${}_3$ via molecular beam epitaxy
• Electrostatic gating and the interference of chiral Majoranas in thin slabs of magnetic topological insulators
• Phases of Quasi-One-Dimensional Fractional Quantum (Anomalous) Hall - Superconductor Heterostructures
• Buried Dirac points in quantum spin Hall insulators: Implications for Majorana Kramers pair-based quantum computing
• Pre-Patterned Superconducting Contacts for Clean Superconductor-Topological Material Interfaces Enabling Long-Range Josephson Coupling