Author/Authors :
Maniwa، نويسنده , , Y. and Muroga، نويسنده , , N. and Tou، نويسنده , , H. and Kikuchi، نويسنده , , K. and Suzuki، نويسنده , , S. and Achiba، نويسنده , , Y. and Kosaka، نويسنده , , M. and Tanigaki، نويسنده , , K. and Iwasa، نويسنده , , Y. and Shimoda، نويسنده , , H. and Mitani، نويسنده , , T.، نويسنده ,
Abstract :
13C-NMR studies of new class of C60 superconductors, (NH3)xNaA2C60 with A=K or Rb, are reported. The results are compared with the other classes of A3C60 superconductors. In fee A3C60, an examination of the modified Korringa relation, T1TK2∼βS showed existence of weak but substantial antiferromagnetic spin fluctuation in A3C60; β=0.40~0.58 with an error of ±20 %. Stoner enhancement factor was also determined as 1∼1.5. The temperature dependent T1TK2, which becomes significant at high temperature (>∼100 K), is suggested to be explained by an enhancement effect related to short mean free path in the present materials. In (NH3)xNaA2C60, a gap-like behavior in temperature dependence of 13C-spin lattice relaxation rate was observed. C60 and NH3 molecular dynamics are also discussed.
Keywords :
superconductor , fullerides , C60 , NMR , Electronic correlation
