DC magnetic penetration depth of UPt3 and Sr2RuO4: implications for the superconducting order parameters

Abstract In order to distinguish the superconducting phases of the title compounds we have studied their DC magnetic properties in low fields with a SQUID magnetometer. The magnetic penetration depth of UPt 3 shows the second superconducting transition at T c − when the field is applied along the c -axis, but not with H ⊥ c . This result, combined with a power law behavior of λ at low temperatures, is most consistent with the two-dimensional E 2u order parameter symmetry. Below 20 mK we find an additional diamagnetic signal which we ascribe to the normal state magnetism. For Sr 2 RuO 4 , supposedly a p-wave superconductor, we find a sharp single diamagnetic transition at 1.08 K showing that our sample is of high quality, but there is no indication of an unusual superconducting behavior.