2 SUCCESSIVE MAGNETIC TRANSITIONS IN Y2CU2O5 STUDIED BY MU-SR

Zero field muon spin rotation and magnetic susceptibility experiments on investigation of magnetic properties of cuprate Y2Cu2O5 have been p erformed in the temperature range 4.2-30 K. Transverse field muSR-expe riments have been also carried out in order to obtain accurate informa tion about transition temperature and to study the influence of the ex ternal magnetic field. Our data show that two magnetic phase transitio ns occur in Y2Cu2O5 with lowering temperature. Upper Neel temperature T(N) = 13 K is consistent with previous experimental data. We obtained the temperature dependence of the local magnetic field on the muon B( mu)(T) in the antiferromagnetic phase. B(mu)(T) reveals a peculiarity (some change of the slope) near the temperature T(N) = 7.5 K, which ca n be interpreted as an additional magnetic phase transition caused by a change in magnetic ordering of the copper subsystem. Applying a smal l external magnetic field 50 Oe leads to smearing of the peculiarity i n B(mu)(T) dependence.