Abstract
The charge localization of single electrons on mesoscopic metallic islands leads to a suppression of the electrical current, known as the Coulomb blockade. When this correction is small, it enables primary electron thermometry, as it was first demonstrated by Pekola et al. (Phys Rev Lett 73:2903, 1994). However, in the low temperature limit, random charge offsets influence the conductance and limit the universal behavior of a single metallic island. In this work, we numerically investigate the conductance of a junction array and demonstrate the extension of the primary regime for large arrays, even when the variations in the device parameters are taken into account. We find that our simulations agree well with measured conductance traces in the submillikelvin electron temperature regime.
Highlights
Single electron charging effects are prominent in isolated nanoscale conductors below a characteristic temperature scale kBT ≪ e2∕2CΣ [1, 2], where kB is the Boltzmann constant, e is the electron charge, and CΣ is the total capacitance of the metallic island
This offset charge depends on the random, uncontrolled population of charge traps at nearby interfaces and charged impurities inside dielectrics [22, 23] leading to a statistical error for primary electron thermometry by Coulomb blockade thermometer (CBT)
Using Markov-chain Monte Carlo simulations, we demonstrated that Coulomb blockade thermometry can be extended beyond the universal regime
Summary
Single electron charging effects are prominent in isolated nanoscale conductors below a characteristic temperature scale kBT ≪ e2∕2CΣ [1, 2], where kB is the Boltzmann constant, e is the electron charge, and CΣ is the total capacitance of the metallic island In this low temperature regime, charge sensing [3] and direct current measurements through tunneling contacts with low conductance, G ≪ e2∕h [4] yield a well-defined number of excess electrons on small metallic islands and an exponentially suppressed tunneling current. Journal of Low Temperature Physics (2021) 204:143–162 results in the breakdown of Coulomb blockade, and it was shown that in this regime, the conductance suppression is universal This enables a primary measurement of the electron temperature [5], which is insensitive to the device geometry, the external magnetic field [6] and the electrostatic environment of the device [7]. We demonstrate the applicability of our numerical results by a direct comparison with ultralow-temperature experimental data, where previous numerical and analytical models fail to describe the conductance of the CBT
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