Scanning magnetic imaging of Sr2RuO4 -: art. no. 012504

We magnetically imaged the ab-plane surface of single crystals of the unconventional superconductor Sr2RuO4, including one sample with an array of microholes, using scanning superconducting quantum interference device and Hall probe microscopy in a dilution refrigerator at low applied magnetic fields. The images show dilute trapped vortices, as would be expected in conventional type-II superconductors, and no other magnetic features. We found no direct signs of the spontaneous magnetization that would be expected in a time-reversal symmetry-breaking (TRSB) superconductor. These measurements set upper limits on the presence of TRSB signatures in this material.