CuNMR/NQR studies on magnetism in impurity/hole-doped spin-ladder compounds

Cu nuclear magnetic resonance (NMR) spectra of impurities (Zn, Ni, and La)- doped spin-1/2 Heisenberg ladder compounds SrCu2O3 (Sr123) are broadened wi th Curie-like temperature (T) dependence. The spectra have been successfull y fit by using a quasi-one-dimensional (Q1D) staggered polarization (SP) mo del. Such a SP has also revealed in Cu NMR measurements of Sr14-xCaxCu24O41 (Cax) with hole-doped ladders. The origin of possible 3D antiferromagnetic (A-F) long-range ordering in (Zn and Ni)-doped Sr123 and Cax around x = 12 at low T is considered to be similar. Once unpaired spins S-0's are induce d and 3D interlayer interaction occurs, the localized spins couple in the w hole system.