Paramagnetism of Copper-Oxygen Chains in High-Temperature YBa_2Cu_3O_(6+δ) Superconductors

摘要

Experimental evidence for the existence of chain paramagnetic Curie-type contributions to the temperature dependence of static magnetic susceptibility χ(T) in the normal (nonsuperconducting) state is obtained for a series of pure YBa_2Cu_3O_(6+δ) high temperature superconductors with different oxygen contents (0.6 < δ ≤ 1). It is shown that the chain contribution is obvious on χ(T) curves only in the T < 150K range of temperatures, grows along with the number of oxygen vacancies in Cu1-O4 chains, and depends on the ordering of these vacancies.