Mv. Eremin et E. Sigmund, ON THE IMPORTANCE OF ANISOTROPIC EXCHANGE COUPLING ON TO THE STRUCTURE OF SPIN-POLARIZED CLUSTERS IN LAYERED CUPRATES, Solid state communications, 91(5), 1994, pp. 367-370
The low energy spectrum of spin-polarized clusters in layered cuprates
is examined. Two types of clusters confining the motion of oxygen hol
es are discussed. The ground state of the pentanuclear copper cluster
has a total spin S = 2, whereas the one of the tetranuclear copper clu
ster is characterised by S = 3/2. Anisotropic exchange coupling splits
the magnetic ground state into a sequence of states, which in a natur
al way provide e.g. an explanation of EPR data for La2CuO4+delta compo
unds.