A coaxial cryogenic probe for quantum Hall effect measurements in the AC regime

The quantum Hall effect is the basis for the realisation of the resistance and impedance units in the revised International System of units of 2019. This paper describes a cryogenic probe that allows to set graphene Hall devices in quantisation conditions in a helium bath (4.2 K) and magnetic fields up to 6 T, to perform precision measurements in the ac regime with impedance bridges. The probe has a full coaxial wiring, isolated from the probe structure, and holds the device in a TO-8 socket. First characterisation experiments are reported on a GaAs device which shows quantisation at 5.5 T.