Аннотации:
The low energy spectrum of spin-polarized clusters in layered cuprates is examined. Two types of clusters confining the motion of oxygen holes are discussed. The ground state of the pentanuclear copper cluster has a total spin S = 2, whereas the one of the tetranuclear copper cluster is characterised by S = 3 2. Anisotropic exchange coupling splits the magnetic ground state into a sequence of states, which in a natural way provide e.g. an explanation of EPR data forLa2CuO4+δ compounds. © 1994.