Hole doping by Li substitution and antiferromagnetism in YBa_2Cu_3O_y studied by neutron powder diffraction measurements

摘要

The magnetic structure of tetragonal insulating YBa_2Cu_(3-x)Li_xO_y has been studied as a function of x and y. The Neel temperature and the mean ordered magnetic moment on the Cu2 sites were determined by neutron powder diffraction measurements. The decrease of these two parameters as compared to YBa_2Cu_3O_6 is much stronger for lithium than for zinc substitution. The difference is quantitatively explained by the presence of holes created in the CuO_2 planes. These holes arise from the substitution of plane Cu~(2+) by Li~+. We suggest an explanation why such holes are not seen for the same substitution of plane Cu~(2+) by Li~+ in orthorhombic superconducting YBa_2Cu_(3-x)Li_xO_(7-δ).