Mesoscopic Transport of Quantum Anomalous Hall Effect in the Submicron Size Regime

The quantum anomalous Hall (QAH) effect has been demonstrated in two-dimensional topological insulator systems incorporated with ferromagnetism. However, a comprehensive understanding of mesoscopic transport in submicron QAH devices has not yet been established. Here we fabricated miniaturized QAH devices with channel widths down to 600 nm, where the QAH features are still preserved. A backscattering channel is formed in narrow QAH devices through percolative hopping between 2D compressible puddles. Large resistance fluctuations are observed in narrow devices near the coercive field, which is associated with collective interference between intersecting paths along domain walls when the device geometry is smaller than the phase coherence length L-phi. Through measurement of size-dependent breakdown current, we confirmed that the chiral edge states are confined at the physical boundary with its width on the order of Fermi wavelength.

Automated summary

This study fabricated miniaturized QAH devices with channel widths down to 600 nm. A backscattering channel was formed in narrow QAH devices through percolative hopping between 2D compressible puddles. Large resistance fluctuations were observed in narrow devices near the coercive field due to collective interference along domain walls. Measurement of size-dependent breakdown current confirmed the confinement of chiral edge states at the physical boundary.