Sign reversal of the oxygen isotope effect on T-c in Sr2RuO4 - art. no. 144514

摘要

We investigated the oxygen isotope effect (IE) on the transition temperature T-c in the spin-triplet superconductor Sr2RuO4 (with the intrinsic T-c0=1.5 K). A clear IE shift in T-c was observed. Moreover, we found that the IE coefficient alpha exhibits an unusual variation with T-c. For lower-T-c crystals containing impurities and defects, alpha is positive and increases with decreasing T-c; alpha (T-c) is described well by the universal behavior expected theoretically. However, for crystals with T-c approaching T-c0, alpha deviates from the universal alpha (T-c) and becomes negative. We discuss its possible mechanism on the basis of existing models. [References: 28]