Universal conductance fluctuations in nanoscale topological insulator devices

Topological materials are promising candidates in fault-tolerant quantum information processing architectures, making it essential to understand the dephasing mechanisms in these materials. Here, we investigate gated, nanoscale mesas fabricated on thin films of cadmium arsenide (Cd3As2), a three-dimensional Dirac semimetal that can be tuned into different topological phases. We observe two independent types of conductance oscillations, one as a function of the applied magnetic field and the other as a function of the gate voltage. Varying the dimensions of the nanostructures allows the discrimination of a variety of scenarios for similar oscillations previously reported in the literature. We conclude that the conductance oscillations are not a signature of topological boundary states per se, but rather are universal conductance fluctuations. These results broadly inform future interpretations of electronic quantum interference in mesoscopic devices made from topological materials.

Automated summary

In this study, we investigate the dephasing mechanisms in topological materials by fabricating gated nanoscale mesas on thin films of cadmium arsenide. We observe two independent types of conductance oscillations related to the applied magnetic field and gate voltage. Varying the nanostructure dimensions allows us to distinguish different scenarios of previously reported similar oscillations. Our conclusion is that these conductance oscillations are not a signature of topological boundary states, but rather universal conductance fluctuations. These findings provide valuable insights for interpreting electronic quantum interference in mesoscopic devices made from topological materials.