Exchange coupling behavior in bimagnetic CoFe2O4/CoFe2 nanocomposite

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

“…One of the simplest routes to form inorganic core/shell nanoparticles arises from the surface treatment of the nanoparticles [89,[116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. This approach has been probably the most developed method to form core/shell nanoparticles and specifically on the study of ferromagnetic/antiferromagnetic systems [36].…”

“…When analyzing the magnetic properties observed experimentally for diverse hard-soft core/shell nanoparticles a spread of different behaviors can be found [91][92][93][94][95][98][99][100][102][103][104]106,107,110,111,114,115,[121][122][123][125][126][127][128][129][130][131][132]136,140,141,143,175,. First, it should be pointed out that given that we are dealing with nanoparticles the core and shell sizes are rather small (i.e., usually smaller than 2 H ), thus, most of the systems exhibit smooth hysteresis loops typical of strongly exchange coupled hard-soft counterparts.…”

On the origin of remanence enhancement in exchange-uncoupled CoFe2O4-based composites

“…In the last years, research on this class of composites has proliferated and successful exchange-coupling and magnetic improvements have been claimed. [12][13][14][15][16][17][18][19] However, the physical mechanisms behind the phenomenology and the extent of effective exchange-coupling are not fully elucidated. 12,13,20 Given that CFO/FeCo composites have been mainly studied on polycrystalline powder form, which are complex systems that can accommodate broad particles size distributions and different compositions and interfaces within the same sample, it must be kept in mind that structural and compositional variations of the individual uncoupled compounds may be responsible for phenomenology that could mistakenly be interpreted as the fingerprint of exchange-spring.…”

Thermal effect on magnetic parameters of high-coercivity cobalt ferrite

“…Cobalt ferrite is a promising material for obtaining optimized exchange-spring magnets [4,15] [15]. All processes utilized to obtain the nanocomposite CoFe 2 O 4 /CoFe 2 employ thermal treatment [4,15].…”

“…All processes utilized to obtain the nanocomposite CoFe 2 O 4 /CoFe 2 employ thermal treatment [4,15]. Is reasonable to suppose that more hard is the precursor material (CoFe 2 O 4 ) better the nanocomposite will be for permanent magnet application.…”