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Title: Is the Sr2RuO4 order parameter two-component
Plain: If the order parameter has two parts, squeezing the crystal along one axis should split the superconducting transition into two; one probe sees a split and another does not.
Precise: Determine whether uniaxial stress along $[100]$ splits $T_c$ of Sr2RuO4 into two thermodynamic transitions, as a two-component order parameter (multidimensional representation or accidental degeneracy) requires. An answer is a thermodynamic detection of the second transition, or a bound on its specific-heat jump below the value predicted by models fitted to the ultrasound data.
Settled by: Calorimetry or elastocaloric measurements under stress with sensitivity below the predicted second-jump size, on the same samples used for muSR.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: contested
Status note: muSR under stress (2021) reported split onsets of superconductivity and time-reversal breaking, while heat capacity under stress found no second transition above a few percent of the main anomaly.
Posed since: (empty)