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Ac susceptibility at low temperatures of Pr_(0.75)Na_(0.25)Mn_(1-x)Fe_xO_3(0≤x≤0.30) is investigated.The peak value of the real component of ac susceptibility x’ at the freezing temperature Tf is suppressed with the increasing frequency. The peak value of x’ shows a linear relation between Tf and the logarithm of the frequencyω.The normalized slope P =△T_f/T_f△lgω,which is much lower than canonical insulating spin glass systems in which 0.06≤P≤0.08.The peak value of the imaginary component of the ac susceptibility x“ at T_f for the x = 0,0.02,0.30 samples increases with increasing frequency,suggesting a cluster glass ground state with a coexistence of charge-ordered phase and correlated ferromagnetic clusters in spin glass matrix.The peak value of x” at T_f for the x = 0.10 sample decreases with increasing frequency,suggesting a phase separation ground state.The peak value of x“ at T_f for the x = 0.05 sample decreases with increasing frequency forω≤52 Hz and increases subsequently till 701 Hz,and then decreases with further increasing frequency forω≤1501 Hz.This complex behaviour is ascribed to the competition between the effects of large and little ferromagnetic clusters in the sample.The ground state of x = 0.05 sample is a transition state from cluster glass to phase separation.
Ac susceptibility at low temperatures of Pr_ (0.75) Na_ (0.25) Mn_ (1-x) Fe_xO_3 (0≤x≤0.30) was investigated. The peak value of the real component of ac susceptibility x ’at the freezing temperature Tf is suppressed with the increasing frequency. The peak value of x ’shows a linear relation between Tf and the logarithm of the frequency ω. normalized slope P = ΔT_f / T_fΔlgω, which is much lower than canonical insulating spin glass systems in which 0.06 ≦ P≤0.08. The peak value of the imaginary component of the ac susceptibility x ”at T_f for the x = 0,0.02,0.30 samples increases with increasing frequency, suggesting a cluster glass ground state with a coexistence of charge-ordered phase and correlated ferromagnetic clusters in spin glass matrix. The peak value of x “at T_f for the x = 0.10 sample decreases with increasing frequency, suggesting a phase separation ground state. The peak value of x ” at T_f for the x = 0.05 sample decreases with increasing frequency forω≤52 Hz and increa ssult to 701 Hz, and then decreases with further increasing frequency forω≤1501 Hz.This complex behavior is ascribed to the competition between the effects of large and little ferromagnetic clusters in the sample. ground state of x = 0.05 sample is a transition state from cluster glass to phase separation.