Magic Doping Fractions in High-Temperature Superconductors

Abstract

We report hole-doping dependence of the in-plane resistivity ρ_{ab} in a cuprate superconductor La_{2-x}Sr_{x}CuO_{4}, carefully examined using a series of high-quality single crystals. Our detailed measurements find a tendency towards charge ordering at particular rational hole doping fractions of 1/16, 3/32, 1/8, and 3/16. This observation appears to suggest a specific form of charge order and is most consistent with the recent theoretical prediction of the checkerboard-type ordering of the Cooper pairs at rational doping fractions x = (2m+1)/2^n, with integers m and n.

5 pages, 3 figure, resubmitted to Phys. Rev. Lett. The Tc vs. x diagram has been added and the discussions have been modified to focus more on the experimental results