Disorder-induced half-integer quantized conductance plateau in quantum anomalous Hall insulator-superconductor structures

Abstract

A weak superconducting proximity effect in the vicinity of the topological transition of a quantum anomalous Hall system has been proposed as a venue to realize a topological superconductor (TSC) with chiral Majorana edge modes (CMEMs). A recent experiment [Science 357, 294 (2017)] claimed to have observed such CMEMs in the form of a half-integer quantized conductance plateau in the two-terminal transport measurement of a quantum anomalous Hall-superconductor junction. Although the presence of a superconducting proximity effect generically splits the quantum Hall transition into two phase transitions with a gapped TSC in between, in this Rapid Communication we propose that a nearly flat conductance plateau, similar to that expected from CMEMs, can also arise from the percolation of quantum Hall edges well before the onset of the TSC or at temperatures much above the TSC gap. Our Rapid Communication, therefore, suggests that, in order to confirm the TSC, it is necessary to supplement the observation of the half-quantized conductance plateau with a hard superconducting gap (which is unlikely for a disordered system) from the conductance measurements or the heat transport measurement of the transport gap. Alternatively, the half-quantized thermal conductance would also serve as a smoking-gun signature of the TSC.

5 pages, 4 figures, 8 pages of supplementary material. Published version

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• Quantum phase transition of chiral Majorana fermion in the presence of disorder
• Intrinsic topological phases in Mn${}_2$Bi${}_2$Te${}_5$ tuned by the layer magnetization
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• Towards the manipulation of topological states of matter: A perspective from electron transport
• Noise signatures for determining chiral Majorana fermion modes
• Optical Responses of Chiral Majorana Edge States in Two-Dimensional Topological Superconductors
• Emergent Josephson current of $N=1$ chiral topological superconductor in quantum anomalous Hall insulator/superconductor heterostructures
• Distinct quantum anomalous Hall ground states induced by magnetic disorders
• Multiple Chiral Majorana Fermion Modes and Quantum Transport
• Majorana-Josephson Interferometer
• Electrically tunable chiral Majorana edge modes in quantum anomalous Hall insulator-topological superconductor systems
• Chiral Majorana Hinge Modes in Superconducting Dirac Materials
• Volkov-Pankratov states in topological superconductors
• Spin-triplet superconductor$-$quantum anomalous Hall insulator$-$spin-triplet superconductor Josephson junctions: $0$-$\pi$ transition, ${\varphi }_0$ phase and switch effects
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• Multicriticality of Two-dimensional Class D Disordered Topological Superconductors
• Topological superconductivity in Fibonacci quasicrystals
• Topological superconductivity in Landau levels
• Controllable Majorana fermions on domain walls of a magnetic topological insulator
• Renormalization group analysis of Dirac fermions with random mass
• Directly probing the chirality of Majorana edge states
• Topology of superconductors beyond mean-field theory
• Inducing superconductivity in quantum anomalous Hall regime
• Electrostatic effects of the MnBi2Te4-superconductor hetero-structures in chiral Majorana search
• From classical to quantum regime of topological surface states via defect engineering
• Chiral topological superconductivity in Josephson junction
• Transport signatures of a quantum spin Hall - chiral topological superconductor junction
• Born approximation study of the strong disorder in magnetized surface states of topological insulator
• Experimental realization of Majorana hinge and corner modes in intrinsic organic topological superconductor without magnetic field at room temperature
• Optical conductivity of the Majorana mode at the s- and d-wave topological superconductor edge
• Disordered Quantum Transport in Quantum Anomalous Hall Insulator-Superconductor Junctions
• Chiral Majorana Edge Modes and Vortex Majorana Zero Modes in Superconducting Antiferromagnetic Topological Insulator
• Majorana Braiding Racetracks from Charge Chern Insulator - Superconductor Hybrids
• Robust quantized thermal conductance of Majorana floating edge bands in d-wave superconductors
• Theory of Tunneling Effect in 1D AIII-class Topological Insulator (Nanowire) Proximity Coupled with a Superconductor
• Electrostatic gating and the interference of chiral Majoranas in thin slabs of magnetic topological insulators
• Magnetic orbital motion and 0.5$e^2/h$ conductance of quantum-anomalous-Hall hybrid strips
• Possible topological phases in quantum anomalous Hall insulator/unconventional superconductor hybrid systems