We report (formula presented) and (formula presented) nuclear magnetic resonance (NMR) measurements on trilayered high-(formula presented) compounds (formula presented) (Tl-1223) that were synthesized at a high pressure and exhibits a high value of superconducting (SC) transition temperature (formula presented) In the SC state, the nuclear spin-lattice relaxation rate (formula presented) reveals a (formula presented) behavior below (formula presented) followed by a (formula presented) behavior at very low temperatures. The results are accounted for by the d-wave pairing model where the presence of the residual density of the states (formula presented) is incorporated at the Fermi level to be consistent with the experiments. The important finding is that the size [in (formula presented) is much smaller for the present compounds of Tl-1223 with (formula presented) than for the previous Tl-2223. Correspondingly, it is shown that an NMR intensity at a satellite peak in the Tl-NMR spectrum, which originates from a possible substitution of Tl for Ca, is much smaller for the former than for the latter. The synthesis technique at a high pressure is found to be a good way to remove such a crystal imperfection due to Tl/Ca intersubstitution. We have demonstrated from a microscopic point of view that as a result of decreasing the degree of disorder effect, the (formula presented) in Tl-1223 has revealed a value higher than 130 K.
|Number of pages
|Physical Review B - Condensed Matter and Materials Physics
|Published - 2002
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics