Coexistence of Superconductor and Spin-Density Wave in (TMTSF)2ClO4: Spatial Structure of the Two-phase State

We report comprehensive (magneto)transport studies of the two-phase state in (TMTSF)2ClO4, where superconducting (SC) phase coexists with spin-density wave insulator (SDW). By tuning the degree of ClO4 anion ordering in controlled manner we drive SDW state and study the evolution of the SC spatial texture. We find that as SDW is suppressed, SC regions initially appear inside the SDW insulator in a form of filaments extended in the interlayer direction and further merge into the two-dimensional sheets across the most conducting axis of the crystal. We demonstrate that almost all our results can be explained within the soliton phase model, though with several assumptions they can also be interpreted by the creation of non-uniform deformations. We believe that the anisotropy is intrinsic to SC/SDW coexistence in quasi one-dimensional superconductors.