Anisotropy and domain state dependent enhancement of single domain ferrimagnetism in cobalt substituted Ni–Zn ferrites

2016 ◽  
Vol 40 (11) ◽  
pp. 9275-9284 ◽  
Author(s):  
Satu G. Gawas ◽  
Sher Singh Meena ◽  
Seikh M. Yusuf ◽  
Vidhyadatta M. S. Verenkar
Keyword(s):  
Magnetic Anisotropy ◽  
Magnetic Domain ◽  
Single Domain ◽  
Blocking Temperature ◽  
Co Substitution ◽  
State Dependent ◽  
Domain State

Reluctance and favorable orientation of magnetic domain with the field at RT and blocking temperature (TB), respectively, as an effect of enhanced magnetic anisotropy by virtue of Co substitution.

Introduction of Fine Engineered Domain Configuration into Potassium Niobate Single Crystals

2007 ◽  
Vol 350 ◽  
pp. 89-92
Author(s):  
Keisuke Yokoh ◽  
Tomomitsu Muraishi ◽  
Song Min Nam ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
...  
Keyword(s):  
Electric Field ◽  
Single Crystals ◽  
Room Temperature ◽  
Single Domain ◽  
Potassium Niobate ◽  
Field Exposure ◽  
Domain State ◽  
Domain Configuration ◽  
Dc Electric Field ◽  
Direction Of Polarization

To induce fine engineered domain configurations into potassium niobate (KNbO3) single crystals, two kinds of methods were performed, i.e., (1) high DC electric field exposure along the opposite direction of polarization of KNbO3 single-domain crystals at room temperature, and (2) introduction of randomly oriented fine domain configuration by heat treatment at 700 °C and then high DC electric field exposure along [001]c direction of KNbO3 multidomain crystals at room temperature. When the method (1) was performed, finally, the poled KNbO3 crystals became to single-domain state again through the formation of multidomain state. On the other hand, the KNbO3 multidomain crystals were obtained by using the method (2), and an enhancement of piezoelectric-related properties was observed.

scholarly journals Synthesis and ESR Study of Transition from Ferromagnetism to Superparamagnetism in La0.8Sr0.2MnO3 Nanomanganite

2020 ◽  
Author(s):  
Mondher Yahya ◽  
Faouzi Hosni ◽  
Ahmed Hichem Hamzaoui
Keyword(s):  
Crystallite Size ◽  
Magnetic State ◽  
Resonance Field ◽  
Magnetic Domain ◽  
Single Domain ◽  
State Transitions ◽  
G Factor ◽  
Domain Structures ◽  
Crystallite Sizes ◽  
Superparamagnetic State

Electron spin resonance (ESR) spectroscopy was used to determine the magnetic state transitions of nanocrystalline La0.8Sr0.2MnO3 at room temperature, as a function of crystallite size. Ferromagnetic nanoparticles having an average crystallite size ranging from 9 to 57 nm are prepared by adopting the autocombustion method with two-step synthesis process. Significant changes of the ESR spectra parameters, such as the line shape, resonance field (Hr), g-factor, linewidth (∆Hpp), and the low-field microwave absorption (LFMA) signal, are indicative of the change in magnetic domain structures from superparamagnetism to single-domain and multi-domain ferromagnetism by increase in the crystallite size. Samples with crystallite sizes less than 24.5 nm are in a superparamagnetic state. Between 24.5 and 32 nm, they are formed by a single-domain ferromagnetic. The multi-domain state arises for higher sizes. In superparamagnetic region, the value of g-factor is practically constant suggesting that the magnetic core size is invariant with decreasing crystallite size. This contradictory observation with the core-shell model was explained by the phenomenon of phase separation that leads to the formation of a new magnetic state that we called multicore superparamagnetic state.

Physical and Magnetic Modification of Co/Pt Multilayers by Ion Irradiation

2002 ◽  
Vol 8 (4) ◽  
pp. 319-332 ◽  
Author(s):  
G.J. Kusinski ◽  
G. Thomas
Keyword(s):  
Magnetic Anisotropy ◽  
Ion Irradiation ◽  
Strain Relaxation ◽  
Magnetic Domain ◽  
Perpendicular Magnetic Anisotropy ◽  
Spin Reorientation ◽  
Microstructural Changes ◽  
Spin Reorientation Transition ◽  
Before And After ◽  
Magnetic Modification

The microstructure of Co/Pt multilayers with large perpendicular magnetic anisotropy (PMA) was investigated before and after energetic ion irradiation. No pronounced microstructural changes were detected at ion doses sufficient to completely reduce the PMA and cause a spin reorientation transition to in-plane. Ion-induced displacement of Co and Pt atoms near Co/Pt interfaces lead to local “roughening” and Co layer strain relaxation, reducing the PMA. The magnetic domain confinement induced by ion irradiation and magnetic patterning by selective ion irradiation were also investigated.

scholarly journals Magnetism of FePt Nanoclusters in Polyimide

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Mircea Chipara ◽  
Tom George ◽  
Yingfan Xu ◽  
Ralph Skomski ◽  
Lanping Yue ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Thermal Annealing ◽  
Blocking Temperature ◽  
Fept Nanoparticles ◽  
Hybrid Films ◽  
Polyimide Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Paramagnetic Impurities ◽  
Spin Resonance

FePt nanoclusters have been implanted onto polyimide films and subjected to thermal annealing in order to obtain a special magnetic phase (L10) dispersed within the polymer. SQUID measurements quantified the magnetic features of the as-prepared and annealed hybrid films. As-implanted FePt nanoparticles in polyimide films exhibited a blocking temperature of 70 ± 5 K. Thermal annealing in zero and 10 kOe applied magnetic field increased the magnetic anisotropy and coercivity of the samples. Wide Angle X-Ray Scattering confirmed the presence of FePt and L10phase. All samples (as deposited and annealed) exhibited electron spin resonance spectra consisting of two overlapping lines. The broad line was a ferromagnetic resonance originating from FePt nanoparticles. Its angular dependence indicated the magnetic anisotropy of FePt nanoparticles. SEM micrographs suggest a negligible coalescence of FePt nanoparticles, supporting that the enhancement of the magnetic properties is a consequence of the improvement of the L10structure. The narrow ESR line was assigned to nonmagnetic (paramagnetic) impurities within the samples consistent with graphite-like structures generated by the local degradation of the polymer during implantation and annealing. Raman spectroscopy confirmed the formation of graphitic structures in annealed KHN and in KHN-FePt.

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