Anisotropic behavior of knight shift in superconducting state of NaxCoO2 center dot yH(2)O

作者：Ihara Y^*; Ishida K; Takeya H; Michioka C; Kato M; Itoh Y; Yoshimura K; Takada K; Sasaki T; Sakurai H; Takayama Muromachi E

来源：Journal of the Physical Society of Japan, 2006, 75(1): 013708.

DOI：10.1143/JPSJ.75.013708

• superconductivity
• hydrate sodium cobalt oxide
• NMR
• spin fluctuations

The Co Knight shift was measured in an aligned powder sample of NaxCoO2 center dot yH(2)O, which shows superconductivity at T-c similar to 4.6 K. The Knight-shift components parallel (K-c) and perpendicular to the c-axis (along the ab plane K-ab) were measured in both the normal and superconducting (SC) states. The temperature dependences of K-ab and K-c are scaled with the bulk susceptibility, which shows that the microscopic susceptibility deduced from the Knight shift is related to Co-3d spins. In the SC state, the Knight shift shows an anisotropic temperature dependence: K-ab decreases below 5 K, whereas K-c does not decrease within experimental accuracy. This result raises the possibility that spin-triplet superconductivity with the spin component of the pairs directed along the c-axis is realized in NaxCoO2 center dot yH(2)O.

• 出版日期2006-1