Temperature Dependence of the Penetration Depth in the Unconventional Superconductor Strontium Ruthenate

We have constructed a high resolution tunnel-diode oscillator based measurement system suitable for measuring the temperature dependence of the magnetic penetration depth of superconductors, lambda(T), at very low temperatures. I report on measurements of lambda(T) in high quality single crystals of the perovskite superconductor Sr2RuO4 down to 0.04 K. We observe quadratic temperature dependence at low temperatures. There is no sign of the crossover or second phase transition predicted for a multi-band superconductor. We argue that power law behavior is consistent with an energy gap with nodes, and discuss how the observed quadratic dependence can arise from several possible mechanisms. We propose that non-local effects may be more important in determining the temperature dependence than impurity scattering, and are sufficient to explain the deviation from the linear behavior expected for local superconductors with line nodes. These results are inconsistent with the candidate p-wave states predicted by leading theories.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Physics

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Yanoff, Brian David

Contributors dc:contributor

• Van Harlingen, Dale J.

• Physics, Condensed Matter

Language dc:language

eng

Identifier

(MiAaPQ)AAI9971229

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/80684