Absence of the 1/8 -anomaly in oxygen isotope effect on YBa${}_2$Cu${}_3$O${}_y$

K. Kamiya, T. Masui, S. Tajima +2

We have prepared oxygen isotope exchanged crystals of impurity-free YBCO with various oxygen concentents, and examined pure doping ($p$) dependance of isotope effect on superconduc…