Tuning the coercivity and exchange bias by controlling the interface coupling in bimagnetic core/shell nanoparticles

Nanoscale ◽  
2017 ◽  
Vol 9 (29) ◽  
pp. 10240-10247 ◽  
Author(s):  
Gabriel C. Lavorato ◽  
Enio Lima ◽  
Horacio E. Troiani ◽  
Roberto D. Zysler ◽  
Elin L. Winkler
Keyword(s):  
Exchange Bias ◽  
Exchange Coupling ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Coupling Energy ◽  
Interface Coupling ◽  
Compositional Modulation ◽  
Core Shell Nanoparticles

The compositional modulation of the interfacial exchange-coupling energy enables control of the coercivity and the exchange bias in antiferromagnetic/ferrimagnetic core/shell nanoparticles.

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 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

Exchange bias behavior of monodisperse Fe3O4/γ-Fe2O3 core/shell nanoparticles

2012 ◽  
Vol 12 (3) ◽  
pp. 808-811 ◽  
Author(s):  
Yosun Hwang ◽  
S. Angappane ◽  
Jongnam Park ◽  
Kwangjin An ◽  
T. Hyeon ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

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

2008 ◽  
Vol 8 (6) ◽  
pp. 2761-2780 ◽  
Author(s):  
Òscar Iglesias ◽  
Amílcar Labarta ◽  
Xavier Batlle
Keyword(s):  
Exchange Bias ◽  
Magnetic Order ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Magnetic Systems ◽  
The Core ◽  
Open Questions ◽  
Exchange Constants ◽  
Core Shell Nanoparticles ◽  
Microscopic Origin

Some of the main experimental observations related to the occurrence of exchange bias in magnetic systems are reviewed, focusing the attention on the peculiar phenomenology associated to nanoparticles with core/shell structure as compared to thin film bilayers. The main open questions posed by the experimental observations are presented and contrasted to existing theories and models for exchange bias formulated up to date. We also present results of simulations based on a simple model of a core/shell nanoparticle in which the values of microscopic parameters such as anisotropy and exchange constants can be tuned in the core, shell and at the interfacial regions, offering new insight on the microscopic origin of the experimental phenomenology. Adetailed study of the magnetic order of the interfacial spins shows compelling evidence that most of the experimentally observed effects can be qualitatively accounted within the context of this model and allows also to quantify the magnitude of the loop shifts in striking agreement with the macroscopic observed values.

Tunability of exchange bias in Ni@NiO core-shell nanoparticles obtained by sequential layer deposition

2015 ◽  
Vol 26 (40) ◽  
pp. 405704 ◽  
Author(s):  
Maria Chiara Spadaro ◽  
Sergio D’Addato ◽  
Paola Luches ◽  
Sergio Valeri ◽  
Vincenzo Grillo ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Layer Deposition ◽  
Core Shell Nanoparticles
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