XXIX International Symposium "Nanophysics and Nanoelectronics", Nizhny Novgorod, March 10-14, 2025
Magnetism, spintronics

Investigation of magnetic correlations in aggregates of superparamagnetic particles in NiFe$_2$O$_4$ powders using ferromagnetic resonance

S. V. Stolyar^ab, I. G. Vazhenina^c, A. O. Shokhrina^ba, E. D. Nikolaeva^b, O. A. Lee^ab, R. S. Iskhakov^c, A. V. Belyi<sup>b

a</sup> Siberian Federal University, Krasnoyarsk
^b Krasnoyarsk Scientific Center of SB RAS
^c L. V. Kirensky Institute of Physics, Siberian Branch of the Russian Academy of Sciences, Krasnoyarsk

Abstract: In order to establish the effect of magnetic interparticle interactions on the dynamic properties of a powder system of superparamagnetic nickel ferrite nanoparticles with an average size of $\sim$4 nm, the temperature dependences of the ferromagnetic resonance (FMR) curve parameters were investigated and analyzed. To describe the experimental results obtained by the FMR method, a model of random magnetic anisotropy is used, which considers the effect of magnetic interparticle interactions on the value of the effective anisotropy constant in an external field. The analysis showed the presence of strong magnetic interactions in the studied system, which disappear when the temperature rises above the blocking temperature and allowed us to obtain quantitative estimates of the intensity and energy of magnetic interparticle interactions, as well as to determine the magnetic anisotropy constant of individual particles (without taking into account the influence of magnetic interparticle interactions).

Keywords: nickel ferrite nanoparticles, ferromagnetic resonance, superparamagnetism, interparticle interaction, length of magnetic correlations.

Received: 06.03.2025
Revised: 06.03.2025
Accepted: 05.05.2025

DOI: 10.61011/FTT.2025.07.61193.30HH-25

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