Nano Letters
Two-Dimensional Quantum Hall Effect and Zero Energy State in Few-Layer ZrTe₅
Nano Letters · 21, 5998-6004 (2021)
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Introduction
Preserving thin ZrTe₅ during fabrication let the team reach a low-temperature hole mobility of about 3,500 cm²/(V·s). In a magnetic field the devices showed integer quantum Hall features and a zero-energy state associated with the bulk gap. The authors discuss the latter as evidence for gapless topological states within that gap.
Author graphical abstract
A closer reading
Two questions run through the paper. A Hall plateau coincident with a minimum in longitudinal conductivity tests whether the film resolves two-dimensional Landau quantization. Interpreting the zero-energy feature is a separate step: the authors infer states in the gap from transport, which calls for a different reading than a direct spatial measurement of edge current at zero field.