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Advanced Experimental Methods for Low-temperature Magnetotransport Measurement of Novel Materials
Published on: January 21, 2016
Non-Hermitian dynamics in quantum anomalous Hall insulators
Le Yi1, Emma Steinebronn1, Asmaul Smitha Rashid2
1Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
Abstract:
Magnetically doped topological insulators (TIs) exhibit two distinct phases: the quantum anomalous Hall (QAH) phase when the Fermi level resides within the surface gap and a metallic phase outside the gap. The QAH phase hosts unidirectional transport channels known as chiral edge states, while the metallic phase exhibits nonreciprocal transport due to unbalanced bidirectional edge states. Using the chiral edge states in Cr-doped (Bi,Sb)2Te3 sandwich structures, we realize non-Hermitian conductance matrices in a one-dimensional Corbino chain with well-defined chirality. By tuning the boundary conditions from periodic to open, we reveal the non-Hermitian skin effect, where eigenstates localize exponentially at one end of the chain. In the metallic phase, we further observe asymmetric, bidirectional coupling between the neighboring sites in the conductance matrix, a direct consequence of the system's intrinsic nonreciprocity. These results establish magnetic TIs as a powerful platform for investigating emergent non-Hermitian phenomena in topological systems.
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The work...

