O-17 AND CU-63 NMR IN UNDOPED AND HOLE-DOPED CU2O3 2-LEG SPIN LADDER A(14)CU(24)O(41) (A(14)=LA6CA8,SR-14,SR11CA3)

We conducted the first O-17 NMR in the S = 1/2 Cu2O3 two-leg spin ladd er, and probed the low energy spin excitations of various momentum tra nsfers up to 850 K. These measurements clearly demonstrate the crossov er from the spin gap to the paramagnetic regime. In the hole-doped lad ders, the crossover is accompanied by changes in electric field gradie nt tensors and charge transport properties, suggesting interplay betwe en spin and charge degrees of freedom.