The ability to controllably tune the heating efficiency of magnetic nanoparticles in an AC magnetic field is highly desirable for their application as mediators of magnetic hyperthermia. Traditional approaches to understand and govern the behavior of hyperthermia mediators include a combination of quasistatic and high-frequency (∼100 kHz) magnetic measurements with subsequent simulation of underlying processes. In this paper, we draw attention to the frequently overlooked fact that for an ensemble of magnetic nanoparticles, there is no straightforward complementarity between the dynamic characteristics obtained under different experimental conditions, as well as between corresponding underlying processes. This paper analyzes mechanisms of AC losses in a fluid based on magnetic nanoparticles, with special emphasis on the domains of their validity, and shows that the mechanisms may become qualitatively different as experimental conditions change from magnetostatic to high-frequency ones. Further, the work highlights new important features which can result from the employment of the refined approaches to interpret experimental results obtained on magnetic fluids based on La1-xSrxMnO3 (x = 0.22) nanoparticles. The gained knowledge provides necessary guidelines for tailoring the properties of magnetic nanoparticles to the needs of self-controlled magnetic hyperthermia.

Two sets of core/shell magnetic nanoparticles, CoFe2O4/Fe3O4 and Fe3O4/CoFe2O4, with a fixed diameter of the core (~ 4.1 and ~ 6.3 nm for the former and latter sets, respectively) and thickness of shells up to 2.5 nm were synthesized from metal chlorides in a diethylene glycol solution. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. The analysis of the results of magnetic measurements shows that coating of magnetic nanoparticles with the shells results in two simultaneous effects: first, it modifies the parameters of the core-shell interface, and second, it makes the particles acquire combined features of the core and the shell. The first effect becomes especially prominent when the parameters of core and shell strongly differ from each other. The results obtained are useful for optimizing and tailoring the parameters of core/shell spinel ferrite magnetic nanoparticles for their use in various technological and biomedical applications.

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Terahertz emission from cubic semiconductor induced by a transient anisotropic photocurrent J. Appl. Phys. 112, 073115 (2012) Resonant plasmonic effects in periodic graphene antidot arrays Appl. Phys. Lett. 101, 151119 (2012) Room temperature terahertz polariton emitter Appl. Phys. Lett. 101, 141118 (2012) Optical parameters of ZnTe determined using continuous-wave terahertz radiation J. Appl. Phys. 112, 063104 (2012) Charge dynamics and electronic structures of monolayer graphene with molecular doping

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