scholarly journals Temperature dependence of magnetic hysteresis of RCox:Co nanocomposites (R=Pr and Sm)

2000 ◽  
Vol 87 (9) ◽  
pp. 6740-6742 ◽  
Author(s):  
J. P. Liu ◽  
R. Skomski ◽  
Y. Liu ◽  
D. J. Sellmyer
2007 ◽  
Vol 20 (8) ◽  
pp. 736-741
Author(s):  
Y Matsumoto ◽  
K Murakami ◽  
Y Kimoto ◽  
K Higuchi ◽  
A Nishida ◽  
...  

2004 ◽  
Vol 5 (6) ◽  
Author(s):  
Yongjae Yu ◽  
Lisa Tauxe ◽  
Bruce M. Moskowitz

2012 ◽  
Vol 4 (2) ◽  
pp. 287 ◽  
Author(s):  
M. R. H. Sarkar ◽  
S. H. Naqib

The nature of the temperature dependence of the zero-field critical current density, Jc0(T), in the CuO2 planes has been investigated for c-axis oriented YBa2Cu3O7-d (Y123) thin films over a range of hole content, p. The hole concentration was varied by changing the oxygen deficiency, d, in the CuO1-d chains by annealing the films under different oxygen partial pressures and temperatures. The Jc0(T) values were extracted from the magnetic hysteresis (M-H) loops obtained at different temperatures. From the analysis of the Jc0(T) data for different sample compositions, we have extracted valuable information regarding the nature of the underlying magnetic flux pinning mechanisms in Y123 superconductors. We have found that the oxygen defects play only a secondary role in pinning of the vortices, the superfluid density, on the other hand plays a significant role. The exponent, n, governing the Jc0(T) behavior for a given sample composition showed a systematic behavior as hole contents are changed. Keywords: Y123 superconductors; Critical current density; Flux pinning.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i2.9653 J. Sci. Res. 4 (2), 287-296 (2012)


2002 ◽  
Vol 746 ◽  
Author(s):  
Fabio C. Fonseca ◽  
Gerardo F. Goya ◽  
Renato F. Jardim ◽  
Reginaldo Muccillo ◽  
Neftalí L. V. Carreño ◽  
...  

ABSTRACTA modified sol-gel technique was used to synthesize nanocomposites of Ni:SiO2 which resulted in Ni nanoparticles embedded in a SiO2 amorphous matrix. Transmission electron microscopy TEM analysis were performed to study the structure and morphology of the magnetic powders. The Ni particles were found to have a good dispersion and a controlled particle size distribution, with average particle radius of ∼ 3 nm. A detailed characterization of the magnetic properties was done through magnetization measurements M(T,H) in applied magnetic fields up to ± 7 T and for temperatures ranging from 2 to 300 K. The superparamagnetic (SPM) behavior of these metallic nanoparticles was inferred from the temperature dependence of the magnetization. The blocking temperature TB, as low as 20 K, was found to be dependent on Ni concentration, increasing with increasing Ni content. The SPM behavior above the blocking temperature TB was confirmed by the collapse of M/MS vs. H/T data in universal curves. These curves were fitted to a log-normal weighted Langevin function allowing us to determine the distribution of magnetic moments. Using the fitted magnetic moments and the Ni saturation magnetization, the radii of spherical particles were determined to be close to ∼ 3 nm, in excellent agreement with TEM analysis. Also, magnetic hysteresis loops were found to be symmetric along the field axis with no shift via exchange bias, suggesting that Ni particles are free from an oxide layer. In addition, for the most diluted samples, the magnetic behavior of these Ni nanoparticles is in excellent agreement with the predictions of randomly oriented and noninteracting magnetic particles. This was confirmed by the temperature dependence of the coercivity field that obeys the relation HC(T) = HC0 [1-(T/TB)1/2] below TB with HC0 ∼ 780 Oe.


2004 ◽  
Vol 272-276 ◽  
pp. E511-E512
Author(s):  
A.A. Parilov ◽  
A.S. Lileev ◽  
Yu.Ya. Lileeva ◽  
M. Reissner ◽  
W. Steiner

AIP Advances ◽  
2017 ◽  
Vol 7 (5) ◽  
pp. 056319 ◽  
Author(s):  
Takuma Sato ◽  
Kaori Nagaoka ◽  
Satoru Kobayashi ◽  
Jayappa Manjanna ◽  
Takeshi Murakami

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