Superconductors with a chiral p-wave pairing are of great interest because they could support Majorana modes that could enable the development of topological quantum computing technologies that are robust against decoherence. Sr 2 RuO 4 is widely believed to be a chiral p-wave superconductor. Yet, the mechanism by which superconductivity emerges in this, and indeed most other unconventional superconductors, remains unclear. Here we show that the local superconducting transition temperature in the vicinity of lattice dislocations in Sr 2 RuO 4 can be up to twice that of its bulk. This is all the more surprising for the fact that disorder is known to easily quench superconductivity in this material. With the help of a phenomenological theory that takes into account the crystalline symmetry near a dislocation and the pairing symmetry of Sr 2 RuO 4, we predict that a similar enhancement should emerge as a consequence of symmetry reduction in any superconductor with a two-component order parameter.
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We acknowledge the useful discussions with S.B. Chung, Y. Maeno, C.C. Tsuei and V. Varkaruk. The work at Penn State is supported by DOE under Grant number DE-FG02-04ER46159. The nanofabrication part of the work is supported by Penn State MRI Nanofabrication Lab under NSF Cooperative Agreement 0335765, NNIN with Cornell University and under NSF DMR 0908700. Y.L. acknowledges partial support from Ministry of Science and Technology of China (Grant 2012CB927403) during the manuscript preparation and development of the theory. The TEM images were obtained at the TEM facility at FSU, supported by the Florida State University Research Foundation, NSF-DMR-0654118 and the State of Florida. K.S. is supported by JQI-NSF-PFC. The work at Tulane is supported by NSF under DMR-1205469.