Ac Susceptibility of Pr sub(0.5)Ca sub(0.5)Mn sub(0.99)Al sub(0.01)O sub(3) at Low Temperatures

Pr0.5Ca0.5Mn0.99Al0.01O3 compound was prepared by standard solid state reaction to study its ac susceptibility at low temperatures. The X-ray powder diffraction patterns show that the compound is single-phase orthorhombic structure. The cusps of charge ordering and the long range AFM order of the "pseudo"-CE type are suppressed with Al dopping in Pr0.5Ca0.5MnO3 compound. ZFC and FC magnetization of this compound bifurcate at Tf. The behavior of ac susceptibility at low temperatures is investigated. The intensity of the real component [whitesquare]' at the freezing temperature Tf is suppressed with the increase of frequency. Tf is linear with the logarithm of the frequency. The normalized slope P = [white triangle up]Tf/Tf[white triangle up]log10 omega , which is much lower than canonical insulating spin glass systems in which 0.06 [< or =] P [< or =] 0.08. The intensity of [whitesquare]" at Tf increases with the increase of frequency. The ground state of this sample is cluster glass.