Raffa F.; Ohno T.; Mali M.; Roos J.; Brinkmann D.; Conder K.; Eremin M.
(1998)
We performed high accuracy 63Cu NQR spin-lattice relaxation and SQUID magnetization measurements on 16O and 18O exchanged YBa2Cu4O8 to determine the isotope shift of the temperature of the opening of the spin gap, T*, and ...