Enhancing T c by Oxygen Isotope Substitution in Cuprates

The phase diagram of doped cuprates is generic. For low dopings a pseudogap is present at temperatures above the superconducting phase. The pseudogap phase is heterogeneous containing superconducting clusters which become phase coherent at T _c (Müller in J. Phys. Cond. Matter 19:251002, 2007). Most recent propositions suggest to increase the cluster size and therefore to enhance T _c . In the present note it is recalled that over a decade ago a giant oxygen isotope effect in low doped LSCO was reported. Thus, if indeed increasing the cluster sizes becomes possible, enhancing T _c towards the onset of the pseudogap phase, then it may be even further enhanced by ¹⁶O to ¹⁸O substitution.