Hole-depletion of ladders in Sr$_{14}$Cu$_{24}$O$_{41}$ induced by   correlation effects
  The hole distribution in Sr$_{14}$Cu$_{24}$O$_{41}$ is studied by low temperature polarization dependent O K Near-Edge X-ray Absorption Fine Structure measurements and state of the art electronic structure calculations that include core-hole and correlation effects in a mean-field approach. Contrary to all previous analysis, based on semi-empirical models, we show that correlations and antiferromagnetic ordering favor the strong chain hole-attraction. For the remaining small number of holes accommodated on ladders, leg-sites are preferred to rung-sites. The small hole affinity of rung-sites explains naturally the 1D - 2D cross-over in the phase diagram of (La,Y,Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$ 
V. Ilakovac, C. Gougoussis, M. Calandra, N. B. Brookes, V. Bisogni, S.   G. Chiuzbaian, J. Akimitsu, O. Milat, S. Tomi\'c, a...
cond-mat.str-el