Large exchange bias with remarkable thermostability in an inverted quasi core/shell CoO/γ-Fe2O3 granular system

Enhanced Magnetic Properties in Antiferromagnetic-Core/Ferrimagnetic-Shell Nanoparticles

“…Interestingly, currently, there is an increasing interest in, so-called, inverted structures (see Fig. 1), where the shell is FM or ferrimagnetic (FiM) and the core is AFM, containing for example Mn oxides12131415161718, Fe oxides1920212223242526272829, Co oxides30313233343536, Cr oxides373839, metallic FePt40 or even multiferroic BiFeO 3 (Refs. 41,42).…”

“…In fact, inverted structures have already demonstrated very large coercivities and loop shifts, tunable blocking temperatures, enhanced Néel temperatures or proximity effects12131415161718192021222324252627282930313233343536373839404142 and have been proposed as potential magnetoelectric random access memories41. However, despite their potential, systematic studies of size effects (i.e., core diameter or shell thickness) are still rather scarce12162225333435. Remarkably, similar effects of the role of the position of the different magnetic phases (core vs shell) also arise in other types of bi-magnetic core/shell nanoparticles such as hard-FM/soft-FM vs. soft-FM/hard-FM nanoparticles, where systems with the hard counterpart in the core can have enhanced or different properties with respect to the ones with soft-FM cores4546.…”

Structural Relaxation and Crystalline Phase Effects on the Exchange Bias Phenomenon in FeF2/Fe Core/Shell Nanoparticles

“…In spite of the great amount of reports on structures exhibiting EB, such as M‐based oxides (M = Mn, [ 24,61,62 ] Fe, [ 61,63,64 ] Co, [ 65–67 ] Cr, [ 68,69 ] among others) and, in particular, on FeF 2 /Fe thin films, [ 70–74 ] at the present, there is a lack of experimental works dealing with FeF 2 /Fe nanoparticles to compare with. This fact could offer an opportunity for experimentalists to look at FeF 2 /Fe core/shell nanoparticles.…”

“…Many works on the EB effect depending on the crystallinity, [ 22,23 ] size (core diameter and shell thickness), [ 24–29 ] position and type of the diverse magnetic phases, [ 21,24,30–33 ] and anisotropy of the involved components [ 34–36 ] have been reported; and attention has been pointed out to the relevance of interface disorder and roughness, uncompensated interfacial spins, complicated interface spin configurations, and the scheme of interactions on the EB properties exhibited by core–shell systems. [ 14,37 ] These facts, along with the continuous enhancement of experimental techniques, which allow the obtention of finely tailored morphologies, give rise to the need for modeling more closely the real structure of the samples in the search of the fundamental features driving the EB phenomenon.…”

Structure, morphology and magnetic properties of flowerlike γ-Fe2O3@NiO core/shell nanocomposites synthesized from different precursor concentrations

“…In addition, Gandha et al point out that the giant EB in Co/CoO core-shell nanowire assemblies has an angular dependence on the value of EB field and the direction of magnetization [13]. Recently, it has been reported that highly homogeneous and inverted core/shell magnetic nanocomposites which demonstrate significant EB effect can be synthesized by simple chemical methods, such as FeO/Fe 3 O 4 [14][15][16], CoO/γ-Fe 2 O 3 [17,18], MnO/γ-Mn 2 O 3 [19,20], and MnO/Mn 3 O 4 systems [20,21].…”