Magnetic properties of the self-doped yttrium manganites YMn_1+xO₃

Magnetic properties of the hexagonal compounds of YMn1+xO3 (0 <= x <= 0.15) have been studied by measuring the dc magnetization, ac magnetization, magnetic hysteresis, and relaxation of the magnetization. All the results give evidence of a spin glass (SG) state at low temperatures in samples with x >= 0.08. This is attributed to the competition between the antiferromagnetic (AFM) matrix and the ferromagnetic (FM) phase induced by the excess Mn. Moreover, careful investigations on the thermoremanent magnetization (TRM) of the sample with x = 0.10 indicate that this SG state is an ideal state with nearly infinite equilibration time and that it shows almost perfect full ageing.