A study of the properties of core/shell/shell Ag/FeCo/Ag nanoparticles

© 2017, Pleiades Publishing, Ltd. The properties of heterophase core/shell/shell Ag/FeCo/Ag nanoparticles synthesized via a plasma method that are promising for biological applications are studied. As is established, the core/shell/shell Ag/FeCo/Ag nanoparticles exhibit a superparamagnetic state at room temperature that allows one to manage the hyperthermia process. The magnetic characteristics of core/shell/shell Ag/FeCo/Ag nanoparticles are interpreted by assuming partial oxidation of the surface layer of a ferromagnetic FeCo shell and formation of the antiferromagnetic Co x Fe 1–x О layer on the FeCo surface. The interaction between the surface antiferromagnetic Co x Fe 1–x О layer and the ferromagnetic FeCо shell causes the emergence of the exchange bias in Ag/FeCo/Ag nanoparticles

編集委員

© 2017, Pleiades Publishing, Ltd. The properties of heterophase core/shell/shell Ag/FeCo/Ag nanoparticles synthesized via a plasma method that are promising for biological applications are studied. As is established, the core/shell/shell Ag/FeCo/Ag nanoparticles exhibit a superparamagnetic state at room temperature that allows one to manage the hyperthermia process. The magnetic characteristics of core/shell/shell Ag/FeCo/Ag nanoparticles are interpreted by assuming partial oxidation of the surface layer of a ferromagnetic FeCo shell and formation of the antiferromagnetic Co x Fe 1–x О layer on the FeCo surface. The interaction between the surface antiferromagnetic Co x Fe 1–x О layer and the ferromagnetic FeCо shell causes the emergence of the exchange bias in Ag/FeCo/Ag nanoparticles

Controlling Magnetization Reversal and Hyperthermia Efficiency in Core-Shell Iron-Iron Oxide Magnetic Nanoparticles by Tuning the Interphase Coupling

Magnetic particle hyperthermia, in which colloidal nanostructures are exposed to an alternating magnetic field, is a promising approach to cancer therapy. Unfortunately, the clinical efficacy of hyperthermia has not yet been optimized. Consequently, routes to improve magnetic particle hyperthermia, such as designing hybrid structures comprised of different phase materials, are actively pursued. Here, we demonstrate enhanced hyperthermia efficiency in relatively large spherical Fe/Fe-oxide core-shell nanoparticles through the manipulation of interactions between the core and shell phases. Experimental results on representative samples with diameters in the range 30-80 nm indicate a direct correlation of hysteresis losses to the observed heating with a maximum efficiency of around 0.9 kW/g. The absolute particle size, the core-shell ratio, and the interposition of a thin wüstite interlayer are shown to have powerful effects on the specific absorption rate. By comparing our measurements to micromagnetic calculations, we have unveiled the occurrence of topologically nontrivial magnetization reversal modes under which interparticle interactions become negligible, aggregates formation is minimized and the energy that is converted into heat is increased. This information has been overlooked until date and is in stark contrast to the existing knowledge on homogeneous particles

Studying the ferromagnetic–paramagnetic phase transition in thin films of L1<inf>0</inf> FePt<inf>1–x</inf>Rh<inf>x</inf>

© 2015, Allerton Press, Inc. FePtRh films with different Rh concentrations (FePt1–xRhx) are fabricated by magnetron sputtering. The magnetic structure and ferromagnetic–paramagnetic phase transition in thin films of L10 FePt1–xRhx with different Rh concentrations (0 ≤ x ≤ 0.40) are studied. It is demonstrated that thin films of FePt1–xRhx with 0 < x < 0.34 are in the ferromagnetic state with high magnetocrystalline anisotropy energy at room temperature, while similar films with 0.34 < x < 0.4 are paramagnetic