Magnetization relaxation and aging in spin-glass (La,Y)1−xCaxMnO3 (x=0.25, 0.3 and 0.5) perovskite

Abstract

Magnetization relaxation and AC-susceptibility measurements have been carried out on a disordered (La,Y)1−xCaxMnO3 (x=0.25, 0.3 and 0.5) system where 〈r(La,Y)〉=〈rPr〉=1.18 Å. Resistivity and low-field susceptibility measurements suggest that the sample with x=0.25 develops a dominant ferromagnetic component below 130 K. With increase of x, the ferromagnetic component decreases at the benefit of a charge-ordered antiferromagnetic one. At low temperatures, for x=0.3, the magnetic frustration due to those two kinds of competing interactions leads to spin-glass-like behavior. This behavior is more pronounced for x=0.5 as the strength of these competing interactions becomes equal. Magnetization relaxation measurements show that aging phenomenon exists in all the samples. The parameters obtained by fitting the M(t) data with a fractional exponential function are correlated with the transport and other magnetic properties.