Simulation of the magnetization reversal of an ensemble of single-domain particles in measurements with a continuous sweep of the magnetic field or temperature

Abstract

An analysis is made of the various protocols of magnetostatic measurements for an ensemble of uniaxial single-domain particles oriented with easy axes along the magnetic field. It is shown that an important role in the magnetization reversal process is played by the continuous sweep of the magnetic field or temperature with time in making various measurements. A new characteristic feature in the temperature dependence of the magnetization rate obtained from the magnetization reversal loop, corresponding to the blocking temperature, is found. It is found that the values of the blocking temperature Tb determined from different magnetostatic measurements are not identical. It is shown that a comparison of the results obtained by these methods requires matching of the effective sweep times for each type of magnetostatic measurement. It is found that taking the measurement time into account in measurements in a constant field for changing temperature modifies the dependence of Tb on the measurement field. It is found that for such measurements the temporal kinetics suppresses the so-called point of irreversibility, and its observation in experiments is an approximate result.

Magnetic susceptibility curves of a nanoparticle assembly, I: Theoretical model and analytical expressions for a single magnetic anisotropy energy

“…Although a few theoretical studies have been devoted to ZFC/FC curves [1][2][3][4][5][6][7], to our knowledge, no theoretical derivation of an analytical expression of the magnetic moment for the entire temperature range for the ZFC and FC curves has been reported. Despite the fact that they are widespread in the nanomagnetism literature, ZFC/FC susceptibility curves remain in many cases underexploited.…”

The influence of intergranular interaction on the magnetization of the ensemble of oriented Stoner–Wohlfarth nanoparticles

“…The magnetization switching process is considered in the framework of Neel discrete orientations model [20] by the solution of a kinetic equation for magnetization similar to Refs. [18,21,22]. Contrary to those papers, here we discuss a possibility of superferromagnetic state creation.…”

“…To model the hysteresis loops, we consider, similar to Ref. [22], the linear field sweep h(t r ) = (t r /t reg )−1 as it realized in real experiments. In the dimensionless variables the equation (2a) assumes the form:…”

“…This means that time dependence of magnetization M at fixed temperature T and magnetic field H can be described (similar to Refs. [18,22]) by Bloch-like equation for z-component of magnetization only. If the interaction term λm is absent in Eq.…”

The magnetization processes and critical transition in a nanogranular magnetic film with perpendicular anisotropy

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