Two-dimensional materials offer a novel platform for the development
of future quantum technologies. However, the electrical characterisation of
topological insulating states, non-local resistance and bandgap tuning in atomically thin
materials, can be strongly affected by spurious signals arising from the measuring
electronics. ...
Two-dimensional materials offer a novel platform for the development
of future quantum technologies. However, the electrical characterisation of
topological insulating states, non-local resistance and bandgap tuning in atomically thin
materials, can be strongly affected by spurious signals arising from the measuring
electronics. Common-mode voltages, dielectric leakage in the coaxial cables and the
limited input impedance of alternate-current amplifiers can mask the true nature of
such high-impedance states. Here, we present an optical isolator circuit which grants
access to such states by electrically decoupling the current-injection from the voltagesensing
circuitry. We benchmark our apparatus against two state-of-the-art measurements:
the non-local resistance of a graphene Hall bar and the transfer characteristic
of a WS2 field-effect transistor. Our system allows the quick characterisation of novel
insulating states in two-dimensional materials with potential applications in future
quantum technologies.
