The role of spin-orbit coupling for the superconductivity in Sr2RuO4

There is strong evidence that the superconducting state of Sr2RuO4 is a tim e reversal symmetry breaking spin-triplet state with gap function of the ba sic form, d(k) = (z) over cap(k(x) +/- ik(y)). Assuming spin-rotation symme try any weak coupling theory leads to six stable degenerate superconducting states, including the one referred to above. The degeneracy is lifted by s pin-orbit coupling. We discuss the conditions for stabilizing the state (z) over cap(k(x) +/- ik(y)). (C) 2000 Elsevier Science B.V. All rights reserv ed.