Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 79 for “"coercivity"”.
-
Design of materials with small magnetic hysteresis: the unexpected role of magnetostriction.
… loop, a conclusion referred to as the ’coercivity paradox.’ We argue that the basic idea of using micromagnetics to predict coercivity is reasonable, but the fault lies with presumptions; one needs to account for large but localized disturbances arising from potent defects. To …
-
Structural and magnetic characterization of Nd-based Nd-Fe and Nd-Fe-Co-Al metastable alloys
… K are typical of a hard magnetic material. The coercivity increases from 0.48 to 4.4 T with the temperature decreasing from 300 to 55 K. The demagnetization curves change from single to two-phase type when the temperature approaches 29 K, ordering temperature of fcc Nd-Fe solid solution. The …
-
Particle shape anisotropy and its effects in AlNiCo and Fe-Cr-Co magnet alloys.
… the properties of magnetic anisoiropy and coercivity) in a manner consistent with a common transformation mechanism. The evidence supports the view that this mechanism is spinodal decomposition, which initially produces an homogeneous, fine shape-anisotropic particle microstructure, and by …
-
A paleomagnetic study of the angrite Sahara 99555
… (NRM) of SAH 99555 appears to have a low-coercivity component probably from a collector's hand magnet or the Earth's field as well as a high-coercivity component, similar to D'Orbigny, another angrite. The paleointensity measurements of the high-coercivity component of SAH 99555,5 agree …
-
Pac-man shaped magnetic tunnel junctions for SEU-resistant CMOS-based magnetic flip flops for space applications
… and IrMn thickness on the exchange field and coercivity of a Co₉₀Fe₁₀/Ir₂₀Mn₈₀ bilayer was studied. Metal mask process was used to fabricate rectangular shaped MTJ devices and the devices were characterized for magnetoresistance. In regards to micromagnetic simulation, the lowest coercivity of …
-
Selective Laser Melting of Finemet Soft Magnetic Material
… amorphous metallic alloys, resulting in low coercivity and high saturation magnetization by facilitating the formation of nanocrystals. An extremely high cooling rate is the foundational factor for controlling the microstructure. Selective Laser Melting (SLM) offers a layer thickness of …
-
Magnetic analysis of nuclear pressure vessel steels and other ferromagnetic materials subject to neutron irradiation and heat treatment
… were established. Microhardness and magnetic coercivity, remanence, permeability, and hysteresis loss were measured as a function of a variety of irradiation and annealing exposures. The results were interpreted in terms of dislocation and magnetic domain wall pinning mechanisms and internal …
-
ELECTROCHEMICAL SYNTHESIS OF MAGNETIC MATERIALS FOR MAGNETIC RECORDING AND MEMS APPLICATIONS
… unstable. In order for bits to be stable, high coercivity media is needed and the flux coming out from the writer head should be high enough to switch the high coercivity medium bits. Hence Cobalt Iron (Co37Fe63) alloys having the highest magnetic flux density of 2.4 T are used for this purpose. …
-
Stress dependence of the magnetic properties of steels
… are used to describe the hysteresis loop. The coercivity (H<sub>c</sub>) ~s the magnetic field value as the induction passes through zero. The remanence (B<sub>r</sub>) is the induction value as the magnetic field passes through zero. The maximum differential permeability (μ'<sub>max</sub>) is …
-
Phase Field Crystal Approach to the Solidification of Ferromagnetic Materials
… hardness. In these simulations we computed the coercivity of the system for different grain sizes and showed that the results are in agreement with the experimental data on magnetic nanocrystalline alloys. This is a quite interesting result which enables us to comprehend the mechanism of the …
-
Synthesis and characterization of magnetically hard Fe-Pt alloy nanoparticles and nano-islands
… 400°C are in the highly ordered fct phase with a coercivity range of 4.7 kOe to 10.7 kOe. Compared with reported high annealing temperatures above 600°C, this fabrication process led to a significantly decreased temperature to achieve the L10 phase FePt by 200°C. A qualitative model was set up to …
-
In situ magnetoresistance measurements during patterning of spin valve devices
… These structures show a progressive increase in coercivity and a transition between single and two-stage reversal with increasing milling depth. A similar patterning technique was applied to unpinned (Ni$_{80}$Fe$_{20}$/Cu/Ni$_{80}$Fe$_{20}$) pseudo spin valve (PSV) structures in order to enhance …
-
Synthesis and Characterization of Nanostructures in Porous Anodic Aluminum Oxide Templates
… by controlling of electrodeposition times. The coercivity of nanostructures increased with increasing aspect ratio. The anisotropy of the arrays was governed by the shape anisotropy of the magnetic objects with different aspect ratios.</p> </p> <p> <p>nanowires in mild-hard alumina and …
-
Vertically and Horizontally Self-assembled Magnetoelectric Heterostructures with Enhanced Properties for Reconfigurable Electronics
… novel material, CuFe2O4 (CuFO), featuring lower coercivity and loss, was chosen to be self-assembled with BFO. This low-loss could increase the efficiency of the ME effect. Also, our findings revealed a much larger α in the vertically integrated heterostructure compared to single-layer CuFO. …
-
Studies of the magnetic properties and microstructures of two rare earth-transition metal type magnetic alloys
… isothermally, it was found that the intrinsic coercivity, microhardness and electrical resistance changed with ageing time, and the ageing temperature also affected the rate of these changes. The magnetic properties of specimens produced from the Nd-Fe-B type alloy were also shown to be …
-
Adsorption of cobalt on gamma-Fe{u2082}O{u2083}
… underwent a thermal treatment to enhance the coercivity. Surface analysis results indicate that the thermal treatment causes a significant diffusion of Co(II) into the bulk γ-Fe₂O₃. The results also suggest that the coercivity enhancement following thermal treatment is largely due to the …
-
Variational Methods for Nonlinear Partial Differential Equations
… of fixed boundary problems. This theorem assumes coercivity and lower semicontinuity conditions of the functional and the energy functional is defined over subsets of Sobolev spaces. After that, the technical concepts associated to this theorem are implemented to study some specific free boundary …
-
Multi-channel tag based on fluid-suspended magnetic microparticles
… determine the demagnetizing field so alter the coercivity. We can detect the presence of a particular particle shape by whether or not there is a switch measured at its specific coercivity. We characterize the particles and find that the coercivity and the ferromagnetic resonance peaks are …
-
Growth, structure and magnetic properties of magnetron sputtered FePt thin films
… at very high pressure (3 Pa). The high coercivity (1.5 T) of granular, magnetic isotropic FePt layers, deposited in Ar discharges, was measured with SQUID magnetometer hysteresis loops. For non-granular films with (001) preferential orientation the coercivity decreased (0.6 T) together …
-
Optimal Control Problems Governed by Nonlinear Partial Differential Equations and Inclusions
… on the definition of an auxiliary operator, coercivity and the S+ -property of operators. The set of solutions of the considered PDE is compact, but the number of solutions and the situation to each other is unknown. This leads to difficulties in deriving necessary optimality conditions. For …
Page 1 of 4