Design and development of a coaxial cryogenic probe for precision measurements of the quantum Hall effect in the AC regime

Abstract

<p class="Abstract"><span lang="EN-US">The quantum Hall effect is the basis for the realisation of the resistance and impedance units in the International System of units since 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, characterization experiments are reported on a GaAs device, showing quantisation at 5.5 T. <span>In the AC regime, <em>multiple-series</em> connections will be employed to minimize the residual error, quantified by electrical modelling of the probe</span>.</span></p>

PTB–INRIM comparison of novel digital impedance bridges with graphene impedance quantum standards

“…The 4TP impedances under comparison are Z 1 , with ports HC1, HP1, LC1 and LP1, and Z 2 , with ports HC2, HP2, LC2 and LP2. When either Z 1 or Z 2 is an ACQHR standard, the device is connected to the bridge by means of a cryogenic coaxial probe [36] implementing the triple-connection scheme. In the following, we shall assume that Z 1 is a calibrated impedance and Z 2 is a possibly uncalibrated one.…”