130-K superconductivity and microwave absorption in Tl-Ba-Ca-Cu-O

In a Tl-Ba-Ca-Cu-O oxide, prepared by means of conventional ceramic technique, the zero-resistance temperature was found to be 127±0.5 K and the diamagnetic transition temperature to be 130±1 K. An ESR measurement shows that there is an intense low-field microwave-absorption peak below $T_c$ ($R=0\mathrm{}$) in the sample. This means that the superconductivity of Tl-Ca-Ba-Cu-O is either associated with the glass feature or with the spin-triplet state of ${\mathrm{Cu}}^{2+}$-${\mathrm{Cu}}^{2+}$ pairs via the exchange interaction mediated by an ${\mathrm{O}}^{-}$ ion, as is indirectly supported by the similar microwave absorption measurement on single-crystal LiNb${\mathrm{O}}_3$: ${\mathrm{Cu}}^{2+}$.