Models for the magnetic ac susceptibility of granular superferromagnetic CoFe/Al${}_2$O${}_3$

Abstract

The magnetization and magnetic ac susceptibility, $\chi ={\chi }^{\prime }-i{\chi }^{\prime \prime }$, of superferromagnetic systems are studied by numerical simulations. The Cole-Cole plot, ${\chi }^{\prime \prime }$ vs. ${\chi }^{\prime }$, is used as a tool for classifying magnetic systems by their dynamical behavior. The simulations of the magnetization hysteresis and the ac susceptibility are performed with two approaches for a driven domain wall in random media. The studies are motivated by recent experimental results on the interacting nanoparticle system Co${}_{80}$Fe${}_{20}$/Al${}_2$O${}_3$ showing superferromagnetic behavior. Its Cole-Cole plot indicates domain wall motion dynamics similarly to a disordered ferromagnet, including pinning and sliding motion. With our models we can successfully reproduce the features found in the experimental Cole-Cole plots.

8 pages, 6 figures

References in corpus (10)

• Creep and depinning in disordered media
• Direct Investigation of Superparamagnetism in Co Nanoparticle Films
• Hysteretic dynamics of domain walls at finite temperatures
• Dipolar interaction between two-dimensional magnetic particles
• Depinning transition and thermal fluctuations in the random-field Ising model
• Dynamic phase transitions in thin ferromagnetic films
• Theory of Hysteresis Loop in Ferromagnets
• Domain Wall Depinning in Random Media by AC Fields
• Thermodynamic perturbation theory for dipolar superparamagnets
• Low-energy properties of two-dimensional magnetic nanostructures: interparticle interactions and disorder effects

Cited by in corpus (12)

• Superparamagnetic nanoparticle ensembles
• Collective states of interacting ferromagnetic nanoparticles
• Unveiling the ac Dynamics of Ferroelectric Domains by Investigating the Frequency Dependence of Hysteresis Loops
• Fingerprinting the magnetic behavior of antiferromagnetic nanostructures using remanent magnetization curves
• Slow dynamics of interacting antiferromagnetic nanoparticles
• Relaxation-to-creep transition of domain-wall motion in two- dimensional random-field Ising model with ac driving field
• Nonsteady dynamic properties of a domain wall for the creep state under an alternating driving field
• Giant Magnetoresistance in Nanogranular Magnets
• On mean field theory for ac-driven elastic interfaces exposed to disorder
• Perturbation theory for ac-driven interfaces in random media
• Coercivity weighted Langevin magnetisation; A new approach to interpret superparamagnetic and nonsuperparamagnetic behaviour in single domain magnetic nanoparticles
• Electron Transport in Nanogranular Ferromagnets