Particle size dependent exchange bias and cluster-glass states in LaMn_0.7Fe_0.3O₃

Abstract

The cluster-glass compound LaMn 0.7 Fe 0.3 O 3 was synthesized with average particle sizes ∼20, ∼90, and ∼300 nm. We observed a shift of the magnetic hysteresis loop in the field axis while the sample was cooled in an external magnetic field. The systematic shift of the hysteresis loops and the cooling field dependence of the shift indicated the phenomenon of exchange bias. The exchange bias field was found to be strongly dependent on the particle size, where the exchange bias field decreased considerably with an increase of particle size, and the weak effect of exchange bias was observed for particles with size ∼300 nm. A cluster-glass state with short range ferromagnetic clusters embedded in the spin-glass like host has been proposed, where the average size of the ferromagnetic cluster increases with particle size.

Large exchange bias in polycrystalline ribbons of Ni56Mn21Al22Si1

“…Our suggestion that the enhanced EB is related to the size of the SPM clusters attained in the course of the field cooling procedure is consistent with the scenario proposed for the explanation of the ZEB effect [19]. It is also worth noting that the dependence of H EB on the cluster size is consistent with the results obtained for manganites where a well defined dependence of H EB on the cooling field [48] as well as on the particle size [49,50] has been observed.…”

The exchange bias effect in phase separated Nd1−xSrxCoO3at the spontaneous ferromagnetic/ferrimagnetic interface

“…Similar features of EB effect was observed for the particle size dependence of EB phenomenon in the cluster-glass compound LaMn 0.7 Fe 0.3 O 3 , where FM clusters are embedded in the SG matrix. [14] The sizes of the FM clusters were found to increase with increasing particle size, which resulted in a decrease in the EB effect. Negligible EB effect was observed for the particles with average size ∼ 300 nm.…”

“…In the high H cool range the feature of H E is reminiscent to that observed for FM/AFM bilayers, [34] AFM-core and FI-shell structure, [28] and unlike to that observed for FM/SG systems. [9,14,23,24,35] have different features of cooling field dependence, where the large values of H cool can not influence the pinned FM spins significantly, which is indicated by the minor change of H E for AFM or FI state. The large reduction of H E around ∼ 37 % is exceptionally observed in Y 0.2 Ca 0.8 MnO 3 for the increase of H cool from 10 kOe to 60 kOe, which is associated with the FM/AFM interface.…”

Influence of cooling field on the magnetic properties of Ni/NiO nanostructure

“…When all the pinned spins are aligned, the increase of H cool cannot contribute to the increase of H E above a certain limit of H cool . Furthermore, large H cool strongly influences the SG or disordered magnetic spins resulting in a considerable decrease of H E , which has been observed in various systems involved with the FM/SG or disordered magnetic interface [18][19][20]. The system exhibiting EB effect must have two different magnetic phases comprising of reversible spins with low magnetic anisotropy and rigid spins having strong anisotropy.…”