Study of Low-Frequency Noise Performance of Nanobridge-Based SQUIDs in External Magnetic Fields

Author

Rozhko, S. ; Hino, Takaya ; Blois, A. ; Hao, Liangliang ; Gallop, John C. ; Cox, David C. ; Romans, E.J.

Author_Institution

London Centre for Nanotechnol., Univ. Coll. London (UCL), London, UK

Volume

23

Issue

3

fYear

2013

fDate

41426

Firstpage

1601004

Lastpage

1601004

Abstract

We report on the low-frequency noise performance of niobium dc superconducting quantum interference devices (SQUIDs), which contain nanobridges fabricated by focused ion beam lithography as the active Josephson elements. The devices have feature sizes down to 70 nm. We have measured devices of different loop sizes in two readout configurations: nano-scale loop sizes in small signal mode using a series SQUID array as a low-temperature pre-amplifier, and larger micron-scale loop sizes in a conventional flux-locked loop. We investigate the different contributions to the low frequency noise and report on electrical measurements made in applied magnetic fields of up to 0.5 T (in-plane) and 0.1 T (perpendicular to the plane) at operating temperatures around 7 K. We compare the measurements with the existing theories of noise in a dc SQUID.

Keywords

SQUIDs; nanotechnology; preamplifiers; superconducting microbridges; active Josephson element; applied magnetic field; dc SQUID array; external magnetic fields; flux locked loop; focused ion beam lithography; low frequency noise performance; nanobridge; nanoscale loop size; niobium dc superconducting quantum interference device; preamplifier; Films; Low-frequency noise; Magnetic field measurement; Noise measurement; SQUIDs; Temperature measurement; Magnetic field sensitivity; nanoscale superconducting quantum interference device (SQUID);

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/TASC.2012.2233537

Filename

6378430