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.

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

References in corpus (11)

• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• 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
• Exotic non-Abelian anyons from conventional fractional quantum Hall states
• Superconducting Proximity Effect on the Edge of Fractional Topological Insulators
• Fractional topological superconductors with fractionalized Majorana fermions
• Current-driven instability of quantum anomalous Hall effect in ferromagnetic topological insulators
• Crossed Andreev effects in two-dimensional quantum Hall systems
• Quantum anomalous Hall edge channels survive up to the Curie temperature
• Conductance oscillations with magnetic field of a two-dimensional electron gas-superconductor junction
• Andreev transport in two-dimensional normal-superconducting systems in strong magnetic fields

Cited by in corpus (21)

• Superconductivity and quantized anomalous Hall in rhombohedral graphene
• Layer-Dependent Quantum Anomalous Hall Effect in Rhombohedral Graphene
• Propagation, dissipation and breakdown in quantum anomalous Hall edge states probed by microwave edge plasmons
• Long-range crossed Andreev reflection in topological insulator nanowires proximitized by a superconductor
• Low-energy modeling of three-dimensional topological insulator nanostructures
• Floquet-Nambu theory of electron quantum optics with superconductors
• Optimizing proximitized magnetic topological insulator nanoribbons for Majorana bound states
• Thermal properties of the superconductor-quantum Hall interfaces
• On-Demand and Tunable Andreev-Conversion of Single-Electron Charge Pulses
• Majorana fermion induced power-law scaling in the violations of the Wiedemann-Franz law
• 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
• Laughlin charge pumping from interplay of chiral Dirac and chiral Majorana modes
• Pre-Patterned Superconducting Contacts for Clean Superconductor-Topological Material Interfaces Enabling Long-Range Josephson Coupling
• 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
• Revealing Superconducting Chiral Edge Modes via Resistance Distributions