scholarly journals Well-controlled exchange bias effect in MnO@Mn3O4 core-shell nanoparticles with an inverted coupling structures

AIP Advances ◽  
2017 ◽  
Vol 7 (4) ◽  
pp. 045316 ◽  
Author(s):  
Ningning Song ◽  
Haitao Yang ◽  
Yi Luo ◽  
Xiao Ren ◽  
Jun Zhou ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Core Shell ◽  
Bias Effect ◽  
Shell Nanoparticles ◽  
Exchange Bias Effect ◽  
Core Shell Nanoparticles

Synthesis and Characterization of Novel Inverted NiO@NixMn1-xO Core-Shell Nanoparticles

MRS Advances ◽  
2017 ◽  
Vol 2 (56) ◽  
pp. 3465-3470
Author(s):  
Samiul Hasan ◽  
R.A. Mayanovic ◽  
Mourad Benamara
Keyword(s):  
Magnetic Measurements ◽  
Magnetic Core ◽  
Primary Objective ◽  
Core Shell ◽  
Zero Field ◽  
Nio Nanoparticles ◽  
Bias Effect ◽  
Shell Nanoparticles ◽  
Exchange Bias Effect ◽  
Core Shell Nanoparticles

ABSTRACTMagnetic core-shell nanoparticles have the potential for numerous applications, such as in magnetic recording media, magnetic resonance imaging, drug delivery or hyperthermia, and spin valves. Inverse core-shell nanoparticles, comprised of an antiferromagnetic (AFM) core covered by a ferromagnetic (FM) or ferrimagnetic (FiM) shell, are of current interest due to the tunability of their magnetic properties. NiO is typically antiferromagnetic in nature and has a Néel temperature of 523 K. Our primary objective in this project is to synthesize and characterize inverted core-shell nanoparticles (CSNs) comprised of a NiO (AFM) core and a shell consisting of a NixMn1-xO (FM/FiM) compound. The synthesis of the CSNs was made using a two-step process. The NiO nanoparticles were synthesized using a chemical reaction method. Subsequently, the NiO nanoparticles were used to grow the NiO@NixMn1-xO CSNs using our hydrothermal nano-phase epitaxy method. XRD structural characterization shows that the NiO@NixMn1-xO CSNs have the rock salt cubic crystal structure throughout. SEM-EDS data indicates the presence of Mn in the CSNs. SQUID magnetic measurements show that the CSNs exhibit AFM/FM or AFM/FiM characteristics with a coercivity field of 425 Oe at 5 K. The field cooled vs zero field cooled hysteresis loop measurements show a significant exchange bias effect between the AFM NiO core and FM/FiM NixMn1-xO shell of the CSNs. The results of additional TEM and magnetic characterization are discussed.

scholarly journals Exchange-bias and magnetic anisotropy fields in core–shell ferrite nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. G. Silva ◽  
J. Depeyrot ◽  
Yu. L. Raikher ◽  
V. I. Stepanov ◽  
I. S. Poperechny ◽  
...  
Keyword(s):  
Spin Glass ◽  
Magnetic Moment ◽  
Exchange Bias ◽  
Uniaxial Anisotropy ◽  
Thermal Fluctuations ◽  
High Amplitude ◽  
Spin Coupling ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

AbstractExchange bias properties of MnFe$$_2$$ 2 O$$_4$$ 4 @$$\gamma$$ γ –Fe$$_2$$ 2 O$$_3$$ 3 core–shell nanoparticles are investigated. The measured field and temperature dependencies of the magnetization point out a well-ordered ferrimagnetic core surrounded by a layer with spin glass-like arrangement. Quasi-static SQUID magnetization measurements are presented along with high-amplitude pulse ones and are cross-analyzed by comparison against ferromagnetic resonance experiments at 9 GHz. These measurements allow one to discern three types of magnetic anisotropies affecting the dynamics of the magnetic moment of the well-ordered ferrimagnetic NP’s core viz. the easy-axis (uniaxial) anisotropy, the unidirectional exchange-bias anisotropy and the rotatable anisotropy. The uniaxial anisotropy originates from the structural core–shell interface. The unidirectional exchange-bias anisotropy is associated with the spin-coupling at the ferrimagnetic/spin glass-like interface; it is observable only at low temperatures after a field-cooling process. The rotatable anisotropy is caused by partially-pinned spins at the core/shell interface; it manifests itself as an intrinsic field always parallel to the external applied magnetic field. The whole set of experimental results is interpreted in the framework of superparamagnetic theory, i.e., essentially taking into account the effect of thermal fluctuations on the magnetic moment of the particle core. In particular, it is found that the rotatable anisotropy of our system is of a uniaxial type.

scholarly journals Exchange Bias Phenomenology and Models of Core/Shell Nanoparticles

ChemInform ◽  
2007 ◽  
Vol 38 (8) ◽  
Author(s):  
Oscar Iglesias ◽  
Amilcar Labarta ◽  
Xavier Batlle
Keyword(s):  
Exchange Bias ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

scholarly journals Shape-dependent exchange bias effect in magnetic nanoparticles with core-shell morphology

2015 ◽  
Vol 92 (6) ◽  
Author(s):  
V. Dimitriadis ◽  
D. Kechrakos ◽  
O. Chubykalo-Fesenko ◽  
V. Tsiantos
Keyword(s):  
Magnetic Nanoparticles ◽  
Exchange Bias ◽  
Shell Morphology ◽  
Core Shell ◽  
Bias Effect ◽  
Exchange Bias Effect
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