Oxygen hole-doping effects on a spin-chain system, Ca2+xY2-x Cu5O10- d (CaYCuO) are reported. CaYCuO is a good specimen to study the magnetic properties of the CuO2 chain at the ground state because it has no complex structure other than the chain and it has hole dopability up to the formal copper valence number of +2.4. Specifically, we can dope holes into the CuO2 chain by substituting Ca2+ for Y3+ or by utilizing oxygen deficiency. After a systematic study of the two methods to dope holes, we found that oxygen doping makes a more critical change in magnetic ordering in the chain than the replacement of Ca2+. Oxygen deficiency effects of the chain on the magnetic properties were explained using a mean field theory. A new relation for the effective hole doping was found as p = x-(2/3)d.
Host: Sang-Wook Cheong