Surface Spin-glass Freezing and Blocking in NiFe2O4 Nanoparticles

2010 ◽  
Vol 1256 ◽  
Author(s):  
Kashif Nadeem ◽  
Heinz Krenn
Keyword(s):  
Low Temperature ◽  
Spin Glass ◽  
Ac Susceptibility ◽  
Sol Gel ◽  
Ferrite Nanoparticles ◽  
Core Shell ◽  
Temperature Hysteresis ◽  
Zero Field ◽  
Temperature Peak ◽  
Surface Spin

AbstractWe prepared single-phase nickel ferrite nanoparticles separated by silicon dioxide using sol-gel method with tetraethyl orthosilicate (TEOS) as a precursor for SiO2. The magnetic properties are investigated by using SQUID-magnetometry over a broad temperature range (4.2 – 350 K), magnetic field (2–70,000 Oe) and frequency (0.1 – 1000 Hz) range. The particle size is in the range 8 – 12 nm. Exchange bias and spin disorder appear at the core-shell interface due to broken bonds on the surface. Disorder and core-shell interaction induces spin-glass freezing which is manifested by a low temperature peak in the AC susceptibility well separated from magnetic blocking peak. This low temperature peak is assigned to spin-glass freezing. The proof of spin-glass freezing is managed by zero field cooled/field cooled (ZFC/FC), frequency and DC field dependence of AC susceptibility, low temperature hysteresis loop and time dependent thermoremanent magnetization at different temperatures. All the measurements stated above signify blocking/unblocking at higher temperatures and surface spin-glass freezing at low temperatures. The aim of our work is to contribute to a better understanding of “spin-frozen” magnetic ferrite nanoparticles at diameters 8 – 12 nm which could be important in future for stabilizing the magnetic state of “core-shell”-structured nanomagnets.

Spin-Glass Behavior and the Magnetic Relaxation Effects in Nd0.90Sr0.10CoO3

2012 ◽  
Vol 557-559 ◽  
pp. 680-683
Author(s):  
Yi Yun Yang
Keyword(s):  
Low Temperature ◽  
Spin Glass ◽  
Mirror Symmetry ◽  
Magnetic Relaxation ◽  
Ac Susceptibility ◽  
Experimental Studies ◽  
Polycrystalline Sample ◽  
Zero Field ◽  
Relaxation Effects ◽  
Field Cooling

The magnetization, ac susceptibility and magnetic relaxation of Nd0.90Sr0.10CoO3polycrystalline sample were systematically investigated in this paper. The experimental studies of susceptibility and magnetic relaxation evidence the existence of a low-temperature spin-glass. A dynamic analysis of ac susceptibility implies a spin-glass transition temperature TSG =12.17 K and the dynamical exponent zv=8. Moreover, low-temperature zero-field cooling and field cooling magnetic relaxation show perfectly mirror symmetry, and field cooling processes relaxation obeys a stretched exponential form. Therefore, our study confirms that the phase separation in Nd0.90Sr0.10CoO3originates from both the ferromagnetic clusters interaction and the spin glasslike phase at low temperature.

scholarly journals Influence of Crystallite Size on the Magnetic Order in Semiconducting ZnCr2Se4 Nanoparticles

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3947 ◽  
Author(s):  
Ewa Malicka ◽  
Małgorzata Karolus ◽  
Tadeusz Groń ◽  
Adrian Gudwański ◽  
Andrzej Ślebarski ◽  
...  
Keyword(s):  
Single Crystal ◽  
Specific Heat ◽  
Spin Glass ◽  
Crystallite Size ◽  
Magnetic Order ◽  
Ac Susceptibility ◽  
High Energy ◽  
Zero Field ◽  
Bulk Single Crystal ◽  
Field Cooling

Structural, electrical, magnetic, and specific heat measurements were carried out on ZnCr2Se4 single crystal and on nanocrystals obtained from the milling of this single crystal after 1, 3, and 5 h, whose crystallite sizes were 25.2, 2.5, and 2 nm, respectively. For this purpose, the high-energy ball-milling method was used. The above studies showed that all samples have a spinel structure, and are p-type semiconductors with less milling time and n-type with a higher one. In turn, the decrease in crystallite size caused a change in the magnetic order, from antiferromagnetic for bulk material and nanocrystals after 1 and 3 h of milling to spin-glass with the freezing temperature Tf = 20 K for the sample after 5 h of milling. The spin-glass behavior for this sample was derived from a broad peak of dc magnetic susceptibility, a splitting of the zero-field-cooling and field-cooling susceptibilities, and from the shift of Tf towards the higher frequency of the ac susceptibility curves. A spectacular result for this sample is also the lack of a peak on the specific heat curve, suggesting a disappearance of the structural transition that is observed for the bulk single crystal.

Surface spin-glass freezing in interacting core–shell NiO nanoparticles

2008 ◽  
Vol 19 (18) ◽  
pp. 185702 ◽  
Author(s):  
E Winkler ◽  
R D Zysler ◽  
M Vasquez Mansilla ◽  
D Fiorani ◽  
D Rinaldi ◽  
...  
Keyword(s):  
Spin Glass ◽  
Core Shell ◽  
Nio Nanoparticles ◽  
Surface Spin

scholarly journals Structural, Electrical, Dielectric, and Magnetic Properties of Cd2+ Substituted Nickel Ferrite Nanoparticles

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
B. H. Devmunde ◽  
A. V. Raut ◽  
S. D. Birajdar ◽  
S. J. Shukla ◽  
D. R. Shengule ◽  
...  
Keyword(s):  
Ac Susceptibility ◽  
Sol Gel ◽  
Interfacial Polarization ◽  
Ferrite Nanoparticles ◽  
Scanning Electron Micrographs ◽  
X Ray Diffraction ◽  
Nickel Ferrite Nanoparticles ◽  
Phase Spinel ◽  
Intergranular Diffusion ◽  
Fe Ions

In the present investigation structural, electric, magnetic, and frequency dependent dielectric properties of Ni1-xCdxFe2O4 ferrite nanoparticles (NPs) (where x=0.2, 0.4, 0.6, and 0.8) prepared by sol-gel autocombustion method were studied. The crystallite size (t) (46.89~58.40 nm) was estimated from X-ray diffraction data with the postconfirmation of single phase spinel structure. Spherical shaped, fused grain nature with intergranular diffusion in Ni1-xCdxFe2O4 NPs was observed in scanning electron micrographs. The value of loss tangent (tan⁡δ) decreases exponentially with an increasing frequency indicating normal Maxwell-Wagner type dielectric dispersion due to interfacial polarization. Decreasing values of Curie temperature (TC) from 860°C to 566°C with increasing Cd2+ content x in Ni1-xCdxFe2O4 NPs were determined from AC-Susceptibility. Activation energy ΔE ranges within 0.03~0.15 eV. Decreasing magnetic saturation Ms, coercivity Hc, and magneton number nB values show the effect on nonmagnetic Cd2+ ions over magnetic Ni2+ and Fe ions.

Distinguishing magnetic blocking and surface spin-glass freezing in nickel ferrite nanoparticles

2011 ◽  
Vol 109 (1) ◽  
pp. 013912 ◽  
Author(s):  
K. Nadeem ◽  
H. Krenn ◽  
T. Traussing ◽  
I. Letofsky-Papst
Keyword(s):  
Spin Glass ◽  
Nickel Ferrite ◽  
Ferrite Nanoparticles ◽  
Nickel Ferrite Nanoparticles ◽  
Surface Spin

Surface spin-glass in cobalt ferrite nanoparticles dispersed in silica matrix

2016 ◽  
Vol 407 ◽  
pp. 241-246 ◽  
Author(s):  
F. Zeb ◽  
W. Sarwer ◽  
K. Nadeem ◽  
M. Kamran ◽  
M. Mumtaz ◽  
...  
Keyword(s):  
Spin Glass ◽  
Cobalt Ferrite ◽  
Ferrite Nanoparticles ◽  
Silica Matrix ◽  
Cobalt Ferrite Nanoparticles ◽  
Surface Spin

scholarly journals Magnetic response of core-shell cobalt ferrite nanoparticles at low temperature

2009 ◽  
Vol 105 (11) ◽  
pp. 113917 ◽  
Author(s):  
K. Maaz ◽  
M. Usman ◽  
S. Karim ◽  
A. Mumtaz ◽  
S. K. Hasanain ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cobalt Ferrite ◽  
Ferrite Nanoparticles ◽  
Core Shell ◽  
Magnetic Response ◽  
Cobalt Ferrite Nanoparticles

scholarly journals Preparation and Characterization of Nickel Ferrite-SiO2/Ag Core/Shell Nanocomposites

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
I. G. Blanco-Esqueda ◽  
G. Ortega-Zarzosa ◽  
J. R. Martínez ◽  
A. L. Guerrero
Keyword(s):  
Silver Nanoparticles ◽  
Nickel Ferrite ◽  
Sol Gel ◽  
Ferrite Nanoparticles ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Magnetic Composites ◽  
Nickel Ferrite Nanoparticles ◽  
Gel Technique

Magnetic composites with silver nanoparticles bonded to their surface were successfully prepared using a simple chemical method. By means of a sol-gel technique, nickel ferrite nanoparticles have been prepared and coated with silica to control and avoid their magnetic agglomeration. The structural and magnetic properties of the nanoparticles were studied in function of the annealing temperature. Then, silver nanoparticles were incorporated by hydrolysis-condensation of tetraethyl orthosilicate, which contains silver nitrate on the surface of the nickel ferrite-SiO2core/shell. Samples were characterized using X-ray diffraction, IR spectroscopy, SEM, and magnetometry. Results show that the silica covered the nickel ferrite nanoparticles and the silver nanoparticles remain stable in the surface of the composite.

NOVEL BINARY SPIN GLASS ALLOYS SYNTHESIZED BY MECHANICAL MILLING

1995 ◽  
Vol 09 (03n04) ◽  
pp. 145-162 ◽  
Author(s):  
G. F. ZHOU ◽  
H. BAKKER
Keyword(s):  
Spin Glass ◽  
Mechanical Milling ◽  
Spin Glasses ◽  
Ac Susceptibility ◽  
Freezing Temperature ◽  
High Energy ◽  
Zero Field ◽  
High Concentration ◽  
Freezing Temperatures ◽  
Field Cooling

A few novel binary spin glass alloys have been successfully synthesized by mechanical milling of ordered intermetallic compounds in a high energy ball mill. These alloys are amorphous Co 2 Ge , atomically disordered crystalline GdAl 2, and ball-milled crystalline and amorphous CoZr. The characteristic features of spin glasses are observed; these are (a) the sharp cusps at the freezing temperature T f in both ac and dc magnetic susceptibility versus temperature curves and their peculiar sensitivity to the external magnetic field; (b) the irreversibility, i.e. the difference in value and shape between the magnetisation versus temperature curves after zero field cooling (ZFC) and field cooling (FC) at temperatures below T f and (c) the displacement of the FC magnetisation curve relative to ZFC curve and the corresponding remanence in the FC curve at low temperatures. The freezing temperatures are 41, 65, 35, and 11 K, respectively, which are defined by the sharp cusps in the lowest field ac susceptibility versus temperature curves. The freezing temperatures are lowered with increasing external field. The common feature of these materials is that all are binary alloys with a rather high concentration of the magnetic component. The discovery of these novel spin glasses is of significance because they not only represent new classes of spin glass materials but also demonstrate the use of mechanical milling as a novel technique to synthesize various new materials such as spin glasses. The results are reviewed briefly.

LOW TEMPERATURE LINEAR DYNAMICAL SUSCEPTIBILITY OF THE ISING SPIN GLASS IN A TRANSVERSE FIELD

2000 ◽  
Vol 14 (18) ◽  
pp. 1843-1857 ◽  
Author(s):  
G. BUSIELLO ◽  
R. V. SABUROVA
Keyword(s):  
Low Temperature ◽  
Spin Glass ◽  
Ac Susceptibility ◽  
Dynamical Behavior ◽  
Transverse Field ◽  
Dipole Magnet ◽  
Ising Spin Glass ◽  
Ising Spin ◽  
Ac Field ◽  
Temperature Equilibrium

Low-temperature equilibrium dynamical behavior of the linear ac susceptibility in d-dimensional Ising spin glass with short-range interactions between spins in transverse field is investigated in terms of droplet model. The real part of linear ac susceptibility [Formula: see text] as functions of temperature T and frequency of external ac field ω is calculated. Frequency and temperature dependence of [Formula: see text] shows a glassy behavior. For instance, we find a broad maximum for [Formula: see text] which shifts towards higher temperatures with increasing frequency of ac-field. The temperature of maximum Tf(ω) depends on frequency and increases with frequency up to the magnitude where [Formula: see text] starts to decrease. A qualitative agreement of our calculations with experimental data, for example, in quantum dipole magnet LiHoxY1-xF4 and proton glasses, is found.

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