Magnetic relaxations in La0.80Ag0.15MnO3+δ nanoparticles

• Published in: Journal of magnetism and magnetic materials Vol. 587
• Main Authors: Mihalik, M., Kovalik, M., Fitta, M., Zentková, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-12-2023
• Subjects: Cole–Cole formalism; Magnetic relaxation; Manganites; Nanoparticles; Spin dynamics; Spin glass; Nanoparticles; Spin dynamics; Cole–Cole formalism; Magnetic relaxation; Spin glass; Manganites
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2023.171253

We have performed the study of spin dynamic on two samples of La0.80Ag0.15MnO3+δ nanoparticles with different ratio of double exchange and superexchange interaction due to heat treatment in Ar or in O2. Our study reports that the change of ground state by annealing affects relaxation processes only slightly. Cole–Cole analysis of the AC susceptibility data revealed the simultaneous existence of two separated relaxation processes with two different relaxation times τ1 of 10−4 s and τ2 of 10−1 s, which can be assigned to the relaxation of different magnetic entities. Faster relaxation processes connected with τ1 are associated with smaller value of Cole–Cole parameter α1 and slower relaxation are characterized by τ2 connected with higher value of Cole–Cole parameter α2. The temperature dependence of τ1 (T) differs from τ2 (T). The aging effect in magnetic relaxation we demonstrate on sample prepared in Ar atmosphere using measurements of the magnetization as a function of observation time which were analysed by stretched exponential expression at low and high temperatures. Our results indicate two different relaxation processes at low and high temperatures, the system of nanoparticles exhibits slow magnetic relaxation, i.e., spin glassy behaviour.
•The study of spin dynamic on two samples of La0.80Ag0.15MnO3+δ nanoparticles with different ratio of double exchange and superexchange interaction revealed that the change of ground state by annealing affects relaxation processes only slightly.•Cole–Cole analysis of the AC susceptibility data revealed the simultaneous existence of two separated relaxation processes with two different relaxation times τ1 of 10−4 s and τ1 of 10−1, which can be assigned to the relaxation of different magnetic entities.•The aging effect in magnetic relaxation were analysed by stretched exponential and our results indicate two different relaxation processes at low and high temperatures, the system of nanoparticles exhibits slow magnetic relaxation, i.e., spin glassy behaviour.