Superferromagnetic response in uniform and sensor modes

Abstract

Properties of magnetic nanoparticles arrays embedded in nonmagnetic insulator or semiconductor substrates are considered. employing the band structure based shell model for a nanoparticles. We show that such systems display ferromagnetic coupling leading to a superferromagnetic structure properties. Superferromagnetic structures are studied accounting for quantum fluctuations due to the discrete level structure and disorder within the randomly jumping interacting states model. The occurrence of self-organized criticality is found to indicate an existence of spinodal regions and critical points in superferromagnetic state equation and phase diagram. The magnetodynamics show jerky behaviour displayed as erratic stochastic discontinuities for magnetic induction. Magnetic noise correlations are proposed as model-independent analytical tools employed in order to specify, quantify and analyse magnetic structure and origin of superferromagnetism. We briefly overview some results for a sensor mode of SFM reactivity associated with spatially local external fields, i.e., a detection of magnetic particles. Favorable designs of superferromagnetic systems for sensor implications are revealed.