Magnetic and magnetoelastic properties of new nanostructured materials and nanoparticles

Magnetic materials are widely used in different technological sectors, covering energy production in electromagnetic machines, theragnostic systems in biomedical applications, sensors and actuators, among others. 

Our group has been working in amorphous and nanocrystalline magnetic materials, focused on soft magnetic alloys obtained by rapid quenching from the melt. In particular, the analysis of the Giant Magnetoimpedance (GMI) effect and Giant Stress Impedance (GSI) have been explored both as additional research tools and in the development of new highly sensitive magnetic and magnetoelastic sensors. These effects are controlled by the skin effect in soft magnetic elements, which is the change in the penetration depth of the high-frequency electric current under external stimuli (magnetic field or stresses, GMI and GSI, respectively). 

On the other side, magnetic nanoparticles represent an active research line in the group, including metal oxides, as TiO₂ or Fe₃O₄, and ferrites as CoZn-Fe₂O₄. Our main interests lie in the design of multifunctional nanoparticles (i.e. ferrimagnetic nucleus and functional shells) for environmental and biomedical applications. For example, magnetically recoverable photocatalysts (Fe₃O₄@TiO₂) have been developed for wastewater treatments (decomposition of organic compounds), where the magnetic nucleus enables the magnetic separation of the photocatalyst.  

Image: Degradation curves,  relative substrate concentration, C/C₀, as a function of the irradiation time, t, of the UV radiation and visible light (Inset). Images of the degradation of the methyl orange under  UV  irradiation at different  times  (t).  (i)  0,  (ii)  60,  and  (iii)  90  min (magnetic separation under the action of a small magnet).

Other examples are the encapsulation of Fe₃O₄ nanoparticles in biocompatible liposomes and lipidic particles for theragnostic platforms (i.e. drug delivery and magnetic hyperthermia).

Image: Temperature increase by applying an alternating magnetic field (499 kHz frequency and 380 G amplitude) for Fe₃O₄ nanoparticles encapsulated in lipid matrix (LNS)

Other magnetic nanoparticle systems under study are iron-based carbonaceous nanomaterials mainly formed by Fe-C nanoparticles surrounded by and graphitic carbon shell. These nanomaterials display properties that can be used in different fields as energy applications, electromagnetic absorption, environmental applications, and biomedical fields.

Image: TEM micrograph from the synthesized iron-based carbonaceous nanoparticle.

Contact: Cristina Gómez Polo