Measurements of excess noise of quantum Hall effect devices

Low-frequency excess noise is a sensitive probe of dissipation in quantum Hall effect (QHE) devices. We performed noise measurements on QHE devices hosted in a cryogen-free dilution refrigerator, with a two-channel correlation spectrum analyzer. Results on a metrology-grade epitaxial graphene QHE sample are reported. At zero or low magnetic field intensity the voltage spectra are dominated by flicker noise. Both flicker noise magnitude and the longitudinal resistance of the device are suppressed at quantization; their evolution as a function of the applied field shows similarity. The activity demonstrates the feasibility of excess noise measurements on metrology-grade QHE samples in a dilution refrigerator environment in the low frequency range, 100 mHz to tens of Hz. The results support noise measurement as an investigation tool of QHE graphene devices, since the drop in measured flicker noise magnitude indicates the onset of quantization.