Unconventional superconductivity in Sr2RuO4

We have performed ZF-mu SR measurements of Sr2RuO4 and have observed a spon taneous magnetic held below T-c. This observation, combined with other symm etry considerations demonstrates that superconductivity in Sr2RuO4 is of 'p -wave' (odd-parity) type. Our transverse field mu SR measurements in the mi xed state with B = 150 G parallel to (c) over cap clearly indicate the pres ence of a square flux lattice. We have analysed the held distribution in te rms of the penetration depth, coherence length and a Fermi surface anisotro py term and found lambda(T = 0) = 1900 Angstrom. lambda(T --> 0) is quite f lat, consistent with a superconducting gap with no nodes as expected for th e E-u (k(x) +/- ik(y)) state. (C) 2000 Elsevier Science B.V. All rights res erved.