Knight shift of 99Ru (99K) has been measured, in the superconducting (SC) state of Sr2 RuO4 with Tc ∼ 1.5 K. The spin component of 99K is negative and approximately one order of magnitude larger than that of 17O Knight shift ( 17K) in the RuO2 plane, indicating that the Ru site feels a stronger hyperfine field originating from Ru-4d electrons. 99K parallel to the RuO2 plane shows no change in the SC state, in agreement with the previous 17K results. The invariance of the spin susceptibility at both Ru and O sites in the SC state gives the decisive evidence that SC pairs are in the spin-triplet state with the SC d-vector perpendicular to the RuO2 plane.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics