Direct observation of chiral edge current at zero magnetic field in odd-layer MnBi${}_2$Te${}_4$

Abstract

The chiral edge current is the boundary manifestation of the Chern number of a quantum anomalous Hall (QAH) insulator. Its direct observation is assumed to require well-quantized Hall conductance, and is so far lacking. The recently discovered van der Waals antiferromagnet MnBi${}_2$Te${}_4$ is theorized as a QAH in odd-layers but has shown Hall resistivity below the quantization value at zero magnetic field. Here, we perform scanning superconducting quantum interference device (sSQUID) microscopy on these seemingly failed QAH insulators to image their current distribution. When gated to the charge neutral point, our device exhibits edge current, which flows unidirectionally on the odd-layer boundary both with vacuum and with the even-layer. The chirality of such edge current reverses with the magnetization of the bulk. Surprisingly, we find the edge channels coexist with finite bulk conduction even though the bulk chemical potential is in the band gap, suggesting their robustness under significant edge-bulk scattering. Our result establishes the existence of chiral edge currents in a topological antiferromagnet and offers an alternative for identifying QAH states.

References in corpus (15)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Quantum Anomalous Hall Effect in Hg${}_{1-y}$Mn${}_y$Te Quantum Wells
• 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
• Electrically detected interferometry of Majorana fermions in a topological insulator
• Intertwined Topological and Magnetic Orders in Atomically Thin Chern Insulator MnBi2Te4
• Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi2Te4 thin films
• Quantum anomalous Hall edge channels survive up to the Curie temperature
• 3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging of quantum materials
• Helical Luttinger liquid on the edge of a 2-dimensional topological antiferromagnet

Cited by in corpus (5)

• Intrinsic magnetic topological insulators of the MnBi${}_2$Te${}_4$ family
• The interplay of ferroelectricity and magneto-transport in non-magnetic moiré superlattices
• Topological Phases in Non-Hermitian Nonlinear-Eigenvalue Systems
• Observation of field-odd and field-free superconducting diode effects in ${\mathrm{Mo}}_2\mathrm{C}$ nanoflakes
• High-Temperature Quantum Anomalous Hall Effect in Buckled Honeycomb Antiferromagnets