The shell thickness dependence of the exchange bias of Fe/Fe3O4 core-shell nanoparticles

Author(s):  
R. Wu ◽  
S. Ding ◽  
Z. Song ◽  
J. Fu ◽  
G. Chen ◽  
...  
2017 ◽  
Vol 122 (6) ◽  
pp. 063902 ◽  
Author(s):  
S. Thomas ◽  
K. Reethu ◽  
T. Thanveer ◽  
M. T. Z. Myint ◽  
S. H. Al-Harthi

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
F. G. Silva ◽  
J. Depeyrot ◽  
Yu. L. Raikher ◽  
V. I. Stepanov ◽  
I. S. Poperechny ◽  
...  

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.


ChemInform ◽  
2007 ◽  
Vol 38 (8) ◽  
Author(s):  
Oscar Iglesias ◽  
Amilcar Labarta ◽  
Xavier Batlle

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2364
Author(s):  
Zhiyuan He ◽  
Chi Zhang ◽  
Rangwei Meng ◽  
Xuanhui Luo ◽  
Mengwei Chen ◽  
...  

In this paper, Ag@SiO2 core-shell nanoparticles (NPs) with different shell thicknesses were prepared experimentally and introduced into the photosensitive layer of mesoscopic hole-conductor-free perovskite solar cells (PSCs) based on carbon counter electrodes. By combining simulation and experiments, the influences of different shell thickness Ag@SiO2 core-shell nanoparticles on the photoelectric properties of the PSCs were studied. The results show that, when the shell thickness of 0.1 wt% Ag@SiO2 core-shell nanoparticles is 5 nm, power conversion efficiency is improved from 13.13% to 15.25%, achieving a 16% enhancement. Through the measurement of the relevant parameters of the obtained perovskite film, we found that this gain not only comes from the increase in current density that scholars generally think, but also comes from the improvement of the film quality. Like current gain, this gain is related to the different shell thickness of Ag@SiO2 core-shell nanoparticles. Our research provides a new direction for studying the influence mechanism of Ag@SiO2 core-shell nanoparticles in perovskite solar cells.


2020 ◽  
Vol 240 ◽  
pp. 122144 ◽  
Author(s):  
Zhiyang Li ◽  
Bridgid Wanjala ◽  
George Cernigliaro ◽  
Dan Nawrocki ◽  
Zhiyong Gu

RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23563-23568 ◽  
Author(s):  
Smita Chaturvedi ◽  
Raja Das ◽  
Pankaj Poddar ◽  
Sulabha Kulkarni

We report a tunable band gap of bismuth ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell.


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