Atypical vortex lattice and the magnetic penetration depth in superconducting Sr2RuO4 deduced by μSR

Abstract

The muon spin rotation (μSR) technique has been applied to determine the behavior of the in-plane magnetic penetration depth (λab) in the vortex state of the unconventional superconductor Sr2RuO4 as a means of gaining insight into its still unknown superconducting order parameter. A recent μSR study of Sr2RuO4 reported a T-linear temperature dependence for λab at low temperatures that was not identified in an earlier μSR study. Here we show that there is no significant difference between the data in the early and recent μSR studies and both are compatible with the limiting low-temperature λab∝T2 dependence expected from measurements of Δλab(T)=λab(T)−λab(0) in the Meissner state by other techniques. However, we argue that at this time there is no valid theoretical model for reliably determining the absolute value of λab in Sr2RuO4 from μSR measurements. Instead, we identify the formation of an unusual square vortex lattice that introduces another constraint on candidate superconducting order parameters for Sr2RuO4.

Source-reported materials — not catalogue approval

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