An analysis is made of published data from measurements of the tempera
ture-and-held dependence of the specific heat in YBaCuO high-temperatu
re superconductors at temperatures below TO K. It is shown that the ''
excess'' contribution to the specific heat can be explained by spin sp
littings in copper-oxygen clusters with S=2. The magnitudes of the nec
essary splittings agree with the available magnetic resonance data. (C
) 1997 American Institute of Physics.