Magnetism in high-Tc superconducting compounds

A review of experimental results concerning the magnetic properties of the copper-oxide high-temperature superconductors (TSC) and their interpretation within the recent theoretical models is given. Crystal structures of four known classes of HTSC (La-, Y-Ba, Bi- and Tl-compounds) are described and their electronic energy structures are discussed on the basis of crystal chemistry. Phase diagrams of La2-xSrxCu4 and YBa2Cu3O7-δ in the (T, x) and (T, δ) planes are given. Magnetic structure of these compounds and their dependence on the variation of dopant concentration x and oxygen vacancies δ are analyzed. A detailed discussion of the magnetic inelastic neutron scattering is presented. The basic theoretical models employed to discuss the physical properties of HTSC are discussed. It is argued that at the present level of experimental investigations of magnetic as well as other properties of HTSC is insufficient to draw a definite conclusion on the validity of the proposed theoretical models of HTSC. Nevertheless, a number of magnetic properties of copper-oxide compounds in the normal state can be explained within the considered models