English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We developed an impedance bridge that operates at cryogenic temperatures(down to 60 mK) and in perpendicular magnetic fields up to at least 12 T. Thisis achieved by mounting a GaAs HEMT amplifier perpendicular to a printedcircuit board containing the device under test and thereby parallel to themagnetic field. The measured amplitude and phase of the output signal allowsfor the separation of the total impedance into an absolute capacitance and aresistance. Through a detailed noise characterization, we find that the bestresolution is obtained when operating the HEMT amplifier at the highest gain.We obtained a resolution in the absolute capacitance of6.4~aF$/\sqrt{\textrm{Hz}}$ at 77 K on a comb-drive actuator, while maintaininga small excitation amplitude of 15~$k_\text{B} T/e$. We show the magnetic fieldfunctionality of our impedance bridge by measuring the quantum Hall plateaus ofa top-gated hBN/graphene/hBN heterostructure at 60~mK with a probe signal of12.8~$k_\text{B} T/e$.

Integrated impedance bridge for absolute capacitance measurements at cryogenic temperatures and finite magnetic fields