Physics - Condensed Matter Journal Club

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Condensed Matter Journal Club: "Approaches and Limitations to Current-Phase Relation Measurements using SQUIDs"

Event Type
Seminar/Symposium
Sponsor
Condensed Matter Journal Club
Location
Loomis 464
Date
Jan 31, 2024   2:00 pm  
Speaker
Jessica Montone (UIUC)
Contact
Jacopo Gliozzi
E-Mail
jglioz2@illinois.edu
Views
44

A Josephson junction (JJ) formed from two superconducting contacts and a material of interest is a powerful tool used to study induced superconductivity. A fundamental property of a JJ is its current-phase relation (CPR), defined as the supercurrent dependence on the phase difference of the superconducting wave functions of the contacts. The "fingerprint" of a JJ -- the CPR provides information on the transport mechanism of Cooper pairs shuttled across the weak link. To date, two techniques have been established for measurements of CPR: the rf-SQUID and the dc-SQUID. The latter method can be further broken down into a dc-SQUID that relies on a reference JJ with a sinusoidal CPR, and one that relies on an asymmetry of critical currents between the studied JJ and the reference JJ. I will present examples of measurements using both techniques, particularly in relation to devices exhibiting topological superconductivity. While it was thought that the asymmetric dc-SQUID critical current dependence should directly reflect the CPR of the JJ being studied, recent findings show that this may not always be the case. Perhaps the asymmetric dc-SQUID is not the ideal "black box" measurement for examining JJs, and instead other CPR measurement methods should be pursued.

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