Evidence of the Superparamagnetic State in the Zero-Field Microwave Susceptibility Spectra of Ferrimagnetic Nanoparticles

• Published in: IEEE magnetics letters Vol. 11; pp. 1 - 5
• Main Authors: Darcheville, Marie, Adenot-Engelvin, Anne-Lise, Boscher, Christophe, Vukadinovic, Nicolas, Lefevre, Christophe, Thiaville, Andre, Sanchez, Clement
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: dynamic magnetic susceptibility; Ferrimagnetism; Ferromagnetic resonance; Magnetic permeability; Magnetic properties; Magnetization; Nanomagnetics; Nanoparticles; Permeability; Physics; Saturation magnetization; superparamagnetism; Temperature; Temperature dependence; Thermal decomposition; dynamic magnetic susceptibility; Nanomagnetics; nanoparticles; superparamagnetism; ferromagnetic resonance
• ISSN: 1949-307X; 1949-3088
• DOI: 10.1109/LMAG.2020.3026228

We investigated the static and dynamic magnetic properties of Zn0.4Fe2.6O4 nanoparticles synthesized by thermal decomposition. Two ranges of diameter were used: small particles (diameter about 6.2 nm) and larger ones (diameter about 22.4 nm). The nanoparticle microstructure was characterized by transmission electron microscopy. The temperature dependence of the zero-field dynamic permeability for both nanoparticle sizes was studied, revealing a superparamagnetic state for the small ones. Effects of the nanoparticle size on the dynamic permeability were analyzied, and linked to the superparamagnetic state. A dynamic susceptibility model was found to reproduce the experimental behavior as well as its temperature dependence.