The penetration depth in Sr2RuO4:: Evidence for orbital-dependent superconductivity

The apparent T-2-temperature dependence of the London penetration depth in Sr2RuO4 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.