CONICET | Buscador de Institutos y Recursos Humanos

The use of FORC diagrams is becoming increasingly popular among researchers devoted tomagnetism and magnetic materials. However, a thorough interpretation of this kind ofdiagrams, in order to achieve quantitative information, requires an appropriate model of thestudied system. For that reason most of the FORC studies are used for a qualitativeanalysis. In magnetic systems thermal fluctuations "blur" the signatures of the anisotropy,volume and particle interactions distributions, therefore thermal effects in nanoparticlessystems conspire against a proper interpretation and analysis of these diagrams. Motivatedby this fact, we have quantitatively studied the degree of accuracy of the informationextracted from FORC diagrams for the special case of single-domain thermal correctedStoner-Wolhfarth (easy axes along the external field orientation) nanoparticles systems. Inthis work, the starting point is an analytical model that describes the behavior of a magneticnanoparticles system as a function of field, anisotropy, temperature and measurement time.In order to study the quantitative degree of accuracy of our model, we built FORC diagramsfor different archetypical cases of magnetic nanoparticles. Our results show that from thequantitative information obtained from the diagrams, under the hypotheses of the proposedmodel, is possible to recover the features of the original system with accuracy above 95%.This accuracy is improved at low temperatures and also it is possible to access to theanisotropy distribution directly from the FORC coercive field profile. Indeed, oursimulations predict that the volume distribution plays a secondary role being the meanvalue and its deviation the only important parameters. Therefore it is possible to obtain anaccurate result for the inversion and interaction fields despite the features of the volumedistribution.

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