THE MAGNETIC STATE OF CU IN THE CUO2-BILAYERS OF PRBA2CU3O6- AN NMR-INVESTIGATION(X )

The antiferromagnetic state in the CuO2-bilayers of PrBa2Cu3O6+x is us ually assumed to be similar to the one in YBa2Cu3O6. One evidence for this is the similarity of the NMR-spectra of the Cu(2)-sites (planes) in both materials. We reinvestigated the NMR-spectra in PrBa2Cu3O6+x-c rystals and observed below 2 K two additional, broad peaks centered ro ughly at 110 and 250 MHz. The signal is only present after applying a field larger than. 5 T below 2.0 K. The frequency and temperature depe ndence of the relaxation rates allows us to ascribe the signal to the Cu(2)-sites, The signal vanishes irreversibly above 2.0 K and reversib ly in fields above 0.5 T, Its intensity versus field shows at all freq uencies a narrow peak near -0.2 T, for the field antiparallel to the o ne inducing the state, which shows the presence of a net polarisation of the spin system.