Dynamic response in Fe-doped La_(0.65)Ca_(0.35)Mn_(1-x)FexO_3:Rare-earth manganites

摘要

We have studied the dynamic response of Fe-doped manganites with ac susceptibility measurements inLa_(0.65)Ca_(0.35)Mn_(1-x)FexO_3 with 0.01#x#0.10 as functions of temperature and dc magnetic field. It is observed that the in-phase part of susceptibility goes through a maximum that is removed on the application of moderate dc field. DC fields suppress both the components (real and imaginary parts) with the strongest effects being at or close to TC. Conduction and ferromagnetism have been consistently suppressed by Fe substitution. Increased spin disorder and decrease in T_C with increasing Fe content are evident. The effect of Fe is seen to be consistent with the disruption of the Mn–Mn exchange possibly due to the formation of magnetic clusters. There is clear correlation between the resistivity and susceptibility. Low-temperature dissipation in high-Fe-doped samples is observed; that is, increasing the Fe leads to increased spin disorder and dissipation at low temperature. The effect of the dc field is discussed in terms of the suppression of spin fluctuations close to T_C.