In the so-called 115 family members with chemical formulae of CeTIn 5 (T=Co, Rh, Ir) and AnTGa5 (An=U, Np, Pu), our analysis of the Knight shift and spin-lattice relaxation rates suggests that larger XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states would favor dwave superconductivity with higher Tc. In order to examine this working hypothesis, the anisotropy ratios of antiferromagnetic fluctuations are derived from our NMR results for the superconductor NpPd 5Al2 and antiferromagnet CePd5Al2, which are tetragonal compounds with a 115-related structure. CePd 5Al2 shows Ising-type anisotropy, which is the same anisotropy as in the ordered state. On the other hand, NpPd5Al 2 shows XY-type anisotropy just above Tc.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)