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Free keywords:
Molluscs, Strontium compounds, London penetration depth, Lows-temperatures, Order parameter, Scanning SQUID microscopy, Single components, Superconducting transitions, Temperature range, Temperature transition, Two-component, Uniaxial strains, Ruthenium compounds
Abstract:
More than two decades after the discovery of superconductivity in Sr2RuO4, it is still unclear whether the order parameter has a single component or two degenerate components. For any two-component scenario, application of uniaxial strain is expected to lift the degeneracy, generating two distinct phase transitions. The presence of a second (lower-temperature) transition may be observable by probes that are sensitive to changes in the London penetration depth, λ, as a function of temperature, T. Here, we use scanning SQUID microscopy combined with a uniaxial strain device to test for a second transition under strain. We only observe a single transition. Within the temperature range where a second transition has been suggested by μSR measurements [Grinenko, Nat. Phys. 17, 748 (2021)1745-247310.1038/s41567-021-01182-7], we further place a tight upper bound of less than 1% on the change in the zero temperature superfluid density ns∝λ-2(0) due to a second transition, suggesting that such a transition does not occur. These results constrain theories of the order parameter in Sr2RuO4. © 2023 American Physical Society.
