Arising from: G.-H. Gweon et al. Nature 430, 187–190 (2004)

The possibility that a pairing boson might act as the 'glue' to bind electrons into a Cooper pair in superconductors with a high critical temperature (T_c) is being actively pursued in condensed-matter physics. Gweon et al.¹ claim that there is a large and unusual oxygen-isotope effect on the electronic structure, indicating that phonons have a special importance in high-temperature superconductors. However, we are unable to detect this unusual oxygen-isotope effect in new data collected under almost identical material and experimental conditions. Our findings point towards a more conventional influence of phonons in these materials.

1. Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
   
2. Department of Applied Physics, Tokyo University of Science, Tokyo 162-8601, Japan
   
3. National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
   
4. Advanced Light Source, Lawrence Berkeley Lab, Berkeley, California 94720, USA.
   
5. Department of Physics, University of Tokyo, Tokyo 113-8656, Japan
   
6. Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
   
7. Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima 739-0046, Japan
   
8. Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan