High-accuracy measurements of the quantum anomalous Hall effect for resistance metrology

This study explores the quantum anomalous Hall effect (QAHE) in V-doped (BiSb)2Te3, a magnetically-doped topological insulators. We use a precision resistance bridge based on a cryogenic current comparator to measure the QAHE at a zero magnetic field with unprecedented uncertainty (ΔRxy/RK ≤ 12 nΩ/Ω). Measurement results obtained at currents between 40 and 300 nA demonstrate the potential of this technology for quantum metrology, offering a path to a primary electrical resistance standard without external magnetic fields.