Heat propagation models for superconducting nanobridges at millikelvin temperatures

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Heat propagation models for superconducting nanobridges at millikelvin temperatures

Blois, A; Rozhko, S; Hao, L; Gallop, JC; Romans, EJ; (2017) Heat propagation models for superconducting nanobridges at millikelvin temperatures. Superconductor Science and Technology , 30 (1) , Article 014003. 10.1088/0953-2048/30/1/014003. Green open access

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Abstract

Nanoscale superconducting quantum interference devices (nanoSQUIDs) most commonly use Dayem bridges as Josephson elements to reduce the loop size and achieve high spin sensitivity. Except at temperatures close to the critical temperature T c, the electrical characteristics of these bridges exhibit undesirable thermal hysteresis which complicates device operation. This makes proper thermal analysis an essential design consideration for optimising nanoSQUID performance at ultralow temperatures. However the existing theoretical models for this hysteresis were developed for micron-scale devices operating close to liquid helium temperatures, and are not fully applicable to a new generation of much smaller devices operating at significantly lower temperatures. We have therefore developed a new analytic heat model which enables a more accurate prediction of the thermal behaviour in such circumstances. We demonstrate that this model is in good agreement with experimental results measured down to 100 mK and discuss its validity for different nanoSQUID geometries.

Type:	Article
Title:	Heat propagation models for superconducting nanobridges at millikelvin temperatures
Open access status:	An open access version is available from UCL Discovery
DOI:	10.1088/0953-2048/30/1/014003
Publisher version:	http://dx.doi.org/10.1088/0953-2048/30/1/014003
Language:	English
Additional information:	Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence (http://creativecommons.org/licenses/by/3.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
Keywords:	nanoSQUID, heat model, retrapping current, superconducting quantum interference device, superconductivity, thermal hysteresis, millikelvin
UCL classification:	UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Electronic and Electrical Eng
URI:	https://discovery.ucl.ac.uk/id/eprint/1531189