The penetration depth in Sr2RuO4: Evidence for orbital dependent superconductivity

TL;DR

This paper investigates the low-temperature behavior of the London penetration depth in Sr2RuO4, attributing it to a multi-gap model with orbital-dependent superconductivity and horizontal line nodes, explaining the observed T^2 dependence.

Contribution

It introduces a multi-gap model with orbital-dependent superconductivity and horizontal line nodes to explain penetration depth behavior in Sr2RuO4, aligning with experimental data.

Findings

Low-temperature behaviors as -T^2 ln T and T^2 in different electromagnetic limits.

Interplay of multiple bands explains T^2-like behavior over a wide temperature range.

Experimental data fits well with the proposed multi-gap model.

Abstract

The apparent $T^2$-temperature dependence of the London penetration depth in Sr$_2$RuO$_4$ is discussed on the basis of a multi-gap model with horizontal line nodes. The influence of the nodes in combination with nonlocal electromagnetic response leads to low-temperature behaviors as $-T^2\ln T$ in the London limit and as $T^2$ in the Pippard limit. These behaviors appear only at very low temperature. On the other hand, the interplay of the superconductivity of different bands is responsible for the observed $T^2$-like behavior over the wide temperature range. The experimental data can be fitted well with a set of material parameters as was used in the specific heat fitting.