K. Magishi et al., CU-63 NMR PROBE OF SUPERCONDUCTING PROPERTIES IN HGBA2CA2CU3O8- A POSSIBLE REASON FOR T-C=133K(DELTA ), Physical review. B, Condensed matter, 53(14), 1996, pp. 8906-8909
Superconducting properties in HgBa2Ca2Cu3O8+delta, with a transition t
emperature of T-c=133 K, have been investigated by measurements of the
nuclear spin-lattice relaxation rate, (63)(1/T-1). It has been found
that the T1T=const behavior, observed well below T-c, arises from comb
ined relaxation channels to vortex cores, as well as from a residual d
ensity of states (DOS), N-res, at the Fermi level associated with the
gapless superconductivity. From the value of T1T=const in the latter c
hannel, the DOS fraction normalized by its value at T-c, N-res/N-Tc, h
as been deduced to be as small as similar to 0.05. Based on the two-di
mensional gapless d-wave model, the T-c reduction rate, Delta T-c/T-c0
, is estimated to be as small as 0.02 for N-res/N-0 similar to 0.05. I
t is pointed out that these measures of the quality of HaBa(2)Ca(2)Cu(
3)O(8+delta) explain why T-c reaches such a high value.