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Magnetometry by a proximity Josephson junction interferometer

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.advisor Peltonen, Joonas T., Dr., Aalto University, Department of Applied Physics, Finland
dc.contributor.author Najafi Jabdaraghi, Robab
dc.date.accessioned 2018-02-14T10:02:55Z
dc.date.available 2018-02-14T10:02:55Z
dc.date.issued 2018
dc.identifier.isbn 978-952-60-7863-2 (electronic)
dc.identifier.isbn 978-952-60-7862-5 (printed)
dc.identifier.issn 1799-4942 (electronic)
dc.identifier.issn 1799-4934 (printed)
dc.identifier.issn 1799-4934 (ISSN-L)
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/30053
dc.description.abstract In quantum technology, several aspects of superconductivity such as proximity effect have studied to develop a wide range of attractive applications at sub-kelvin temperatures. A new type of interferometer based on the proximity effect, taking place around transparent interfaces between normal- and superconducting metals, the Superconducting Quantum Interference Proximity Transistor (SQUIPT), relies on the phase dependence of the density of states in the proximized weak link. The SQUIPT devices offer the possibility to realize sensitive low-dissipation magnetometers compared to conventional DC SQUIDs. In this thesis, we investigate the development of the sensitive SQUIPT magnetometers. The first part of the thesis covers the characterization of non-hysteretic SQUIPTs with enhanced responsivity. In these structures, we demonstrate magnetic flux modulation of the device characteristics displaying no hysteresis at low temperatures by simply increasing the Josephson inductance of the weak link compared to self-inductance of the superconducting loop in the device. As a consequence, improvement in magnetic field responsivity is achievable. We then turn to the implementation of SQUIPT devices based on different fabrication methods and superconductor materials for improving the device performance. In this aspect, we fabricate and characterize niobium-based SNS devices utilizing two separate lithography and deposition steps with strong Ar ion cleaning in between. We further investigate a prototype hybrid SQUIPT device based on an Nb-Cu-Nb SNS junction with a conventional Al probe in tunnel junction. In the third part of the thesis, we present the flux noise characterization of a SQUIPT device using simultaneous measurement of DC transport properties and shot noise. To probe the noise, we use a cryogenic amplifier operating at frequencies in the range of a few MHz. We adapt this technique for flux noise measurements in SQUIPTs, adaptable also to low-temperature shot noise measurements of other nonlinear devices with high impedance. In order to investigate flux noise of SQUIPTs, we develop a model allowing one to optimize the figures of merit of the magnetometers such as the noise-equivalent flux. en
dc.format.extent 92 + app. 46
dc.format.mimetype application/pdf en
dc.language.iso en en
dc.publisher Aalto University en
dc.publisher Aalto-yliopisto fi
dc.relation.ispartofseries Aalto University publication series DOCTORAL DISSERTATIONS en
dc.relation.ispartofseries 34/2018
dc.relation.haspart [Publication 1]: R. N. Jabdaraghi, M. Meschke, and J. P. Pekola. Non-hysteretic superconducting quantum interference proximity transistor with enhanced responsivity. Applied Physics Letters 104, 082601 (4 pages), February 2014. DOI: 10.1063/1.4866584
dc.relation.haspart [Publication 2]: R. N. Jabdaraghi, J. T. Peltonen, O.-P. Saira, and J. P. Pekola. Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces. Applied Physics Letters 108, 042604 (5 pages), January 2016. DOI: 10.1063/1.4940979
dc.relation.haspart [Publication 3]: R. N. Jabdaraghi, D. S. Golubev, J. P. Pekola, and J. T. Peltonen. Noise of a superconducting magnetic flux sensor based on a proximity Josephson junction. Scientific Reports 7, 8011 (13 pages), August 2017. DOI: 10.1038/s41598-017-08710-7
dc.relation.haspart [Publication 4]: R. N. Jabdaraghi, J. T. Peltonen, D. S. Golubev, and J. P. Pekola. Magnetometry with Low-Resistance Proximity Josephson Junction. Journal of Low Temperature Physics, (10 pages), January 2018, DOI: 10.1007/s10909-018-1863-x
dc.subject.other Physics en
dc.title Magnetometry by a proximity Josephson junction interferometer en
dc.type G5 Artikkeliväitöskirja fi
dc.contributor.school Perustieteiden korkeakoulu fi
dc.contributor.school School of Science en
dc.contributor.department Teknillisen fysiikan laitos fi
dc.contributor.department Department of Applied Physics en
dc.subject.keyword superconductivity en
dc.subject.keyword proximity effect en
dc.subject.keyword SNS weak link en
dc.subject.keyword tunnel junction en
dc.subject.keyword SQUID en
dc.subject.keyword SQUIPT en
dc.identifier.urn URN:ISBN:978-952-60-7863-2
dc.type.dcmitype text en
dc.type.ontasot Doctoral dissertation (article-based) en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.contributor.supervisor Pekola, Jukka P., Prof., Aalto University, Department of Applied Physics, Finland
dc.opn Taddei, Fabio, Dr., NEST, Istituto Nanoscienze-CNR, Pisa, Italy
dc.contributor.lab PICO group en
dc.rev Kafanov, Sergey, Dr., Lancaster University, United Kingdom
dc.rev Kempf, Sebastian, Dr., Heidelberg University, Germany
dc.date.defence 2018-02-23
local.aalto.acrisexportstatus checked
local.aalto.formfolder 2018_02_14_klo_10_25
local.aalto.archive yes

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