17O and 63,65Cu NMR of undoped and hole-doped Cu2O3 two-leg spin-ladder A14Cu24O41 up to 850K

We carried out the first 17O as well as 63,65Cu NMR in the S=12 Cu2O3 two-leg spin-ladder, and observed the crossover of magnetic excitations from the spin gap to the paramagnetic regime. In hole-doped ladders, the magnetic crossover is accompanied by the transfer of holes from the CuO2 chain layer to the Cu2O3 ladder layer.