Non-Majorana Origin of the Half-Quantized Conductance Plateau in Quantum Anomalous Hall Insulator and Superconductor Hybrid Structures

Abstract

A quantum anomalous Hall (QAH) insulator coupled to an s-wave superconductor is predicted to harbor a topological superconducting phase, the elementary excitations of which (i.e. Majorana fermions) can form topological qubits upon non-Abelian braiding operations. A recent transport experiment interprets the half-quantized two-terminal conductance plateau as the presence of chiral Majorana fermions in a millimeter-size QAH-Nb hybrid structure. However, there are concerns about this interpretation because non-Majorana mechanisms can also generate similar signatures, especially in a disordered QAH system. Here, we fabricated QAH-Nb hybrid structures and studied the QAH-Nb contact transparency and its effect on the corresponding two-terminal conductance. When the QAH film is tuned to the metallic regime by electric gating, we observed a sharp zero-bias enhancement in the differential conductance, up to 80% at zero magnetic field. This large enhancement suggests high probability of Andreev reflection and transparent interface between the magnetic topological insulator (TI) and Nb layers. When the magnetic TI film is in the QAH state with well-aligned magnetization, we found that the two-terminal conductance is always half-quantized. Our experiment provides a comprehensive understanding of the superconducting proximity effect observed in QAH-superconductor hybrid structures and shows that the half-quantized conductance plateau is unlikely to be induced by chiral Majorana fermions.

arXiv comment17 pages, 4 figures. Comments are welcome. Supplementary materials will be provided upon request

References in corpus (35)

• Topological insulators and superconductors
• Fault-tolerant quantum computation by anyons
• Non-Abelian Anyons and Topological Quantum Computation
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Majorana Fermions and a Topological Phase Transition in Semiconductor-Superconductor Heterostructures
• 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
• Search for Majorana fermions in superconductors
• High-precision realization of robust quantum anomalous Hall state in a hard ferromagnetic topological insulator
• Trajectory of Anomalous Hall Effect toward the Quantized State in a Ferromagnetic Topological Insulator
• Scale-Invariant Dissipationless Chiral Transport in Magnetic Topological Insulators beyond the Two-Dimensional Limit
• Chiral Topological Superconductor From the Quantum Hall State
• Chiral Majorana edge state in a quantum anomalous Hall insulator-superconductor structure
• Realization of the Axion Insulator State in Quantum Anomalous Hall Sandwich Heterostructures
• Topological superconductivity in monolayer transition metal dichalcogenides
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Chiral topological superconductor and half-integer conductance plateau from quantum anomalous Hall plateau transition
• Tailoring tricolor structure of magnetic topological insulator for robust axion insulator
• Inducing Superconducting Correlation in Quantum Hall Edge States
• Possible Topological Superconducting Phases of MoS${}_2$
• Metal-to-Insulator Switching in Quantum Anomalous Hall States
• Zero-field dissipationless chiral edge transport and the nature of dissipation in the quantum anomalous Hall state
• Universal Scaling of Quantum Anomalous Hall Plateau Transition
• Observation of the zero Hall plateau in a quantum anomalous Hall insulator
• Part-per-million quantization and current-induced breakdown of the quantum anomalous Hall effect
• Coincidence of Superparamagnetism and perfect quantization in the Quantum Anomalous Hall state
• Scaling of the Quantum Anomalous Hall Effect as an Indicator of Axion Electrodynamics
• A mechanism of $\frac{e^2}{2h}$ conductance plateau without 1D chiral Majorana fermions
• Giant negative magnetoresistance driven by spin-orbit coupling at the LAO/STO interface
• Large discrete jumps observed in the transition between Chern states in a ferromagnetic Topological Insulator
• Zero-field quantum anomalous Hall metrology as a step towards a universal quantum standard unit system
• Disorder-induced half-integer quantized conductance plateau in quantum anomalous Hall insulator-superconductor structures
• Current-driven instability of quantum anomalous Hall effect in ferromagnetic topological insulators
• Epitaxy and Structural Properties of (V,Bi,Sb)${}_2$Te${}_3$ Layers Exhibiting the Quantum Anomalous Hall Effect

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