Tuning the magnetic anisotropy in exchange coupled bimagnetic core/shell nanoparticles

F. FABRIS; G.C. LAVORATO; E. LIMA JR.; C. QUINTEROS; L. NEÑER; M. GRANADA; M. SIRENA; R.D. ZYSLER; H.E. TROIANI; V. LEBORÁN; F. RIVADULLA; E.L. WINKLER

Mainz

Simposio; 9th Joint European Magnetic Symposia (9th JEMS 2018); 2018

JEMS

The advance in the fabrication methods allows the design and production of new nanostructures with tailored properties. In particular, the combination of proper materials in a single nanoparticle with a core/shell structure, and the possibility to form large areas of self-assembled membrane, opens a wide range of possibilities to control the magnetoelectric response of these nanostructures. One of the characteristic that determines the range of application of each system is the magnetic anisotropy, which can be tuned by the interface exchange coupling in bimagnetic nanoparticles (NPs). In this work we present the evolution of the magnetic anisotropy of exchange coupled core/shell systems as a function of the shell composition. We studied two systems, one formed by an AFM CoO core and the other one is formed by FiM half-metallic Fe3O4 core, both encapsulated with a Co1−xZnxFe2O4 (x = 0?1) shell. The results show that the effective magnetic anisotropy of core/shell NPs can be precisely tuned by replacing the Co2+ with Zn2+ ions in the shell. Large area of Fe3O4/Co1−xZnxFe2O4 self-assembled NPs was then produced to develop tunnel magnetoresistance devices. We found that the magnetoresistance curves are related to the field dependence of the magnetization, where the magnetoresistance switching field is correlated to the coercivity field of the systems. These results are very promising for designing novel devices with tuned magnetoelectric properties based in core/shell NPs.