Papers by Keyword: Permalloy

Abstract: In this work, we have investigated the localized surface plasmon resonance profile of promising non-noble metals such as nickel (Ni), iron (Fe), and permalloy (Ni₈₀Fe₂₀) as an alternative plasmonic material. The nanoparticle formed a sphere with varying the diameter from 10 nm to 200 nm with increment 10 nm, and the medium of nanoparticles is air (1+0i). The calculation was carried out by metallic nanoparticle boundary element method package. Furthermore, our result shows that increasing diameter of particles (iron, nickel, and permalloy) would increase the efficiency of ratio scattering to absorption, and the LSPRs peak led to shift to lower energy (red-shift). The ratio of scattering to absorption indicates a strengthening of radiative damping in large particle-size which largely used in biological cell imaging. However, iron’s efficiency much lower than nickel and permalloy. For example, at the highest diameter, such 200 nm, the efficiency of iron is just over around 1.25 while nickel and permalloy well under nearly 2.0. In addition, nickel and permalloy’s LSPR happened in visible range. Our results serve a systematic understanding of the shifting spectrum pattern for prospective ferromagnetic materials

Abstract: The structure, magnetic properties, ferromagnetic resonance and giant magnetoimpedance effect (GMI) were studied in Fe_xNi_100-x thin films and multilayered systems having compositions with small deviation from zero magnetostriction in order to find the best conditions for possible applications in the area of small pressure sensors. A comparative analysis of the effective magnetization and g-factor was carried out for the thin films of Fe_xNi_100-x (x = 19.8, 17.5, 15.0, 11.9) alloys. Comparison of the concentration dependences for static 4πM_s and dynamic 4πM_eff magnetization values allows to select a narrow interval of concentrations around Fe₁₅Ni₈₅ for the development of a microfluidic small pressure sensitive elements based on GMI effect. The maximum value of GMI ratio (ΔZ/Z) ratio shows linear dependence on the iron content in the Fe_xNi_100-x alloy for the concentration range under consideration.

Abstract: The magnetic static permeability of sputtered FeCuNbSiB and electrodeposited NiFe patterns with thicknesses varying from 0.1 to 8 μm has been studied. The permeability varies proportionally with the pattern size/thickness ratio, like for uniformly magnetized patterns. Different hypothesis on this variation have been investigated and a critical analysis favors a demagnetizing effect. The comparison between experimental results and the theoretical value of the demagnetizing factor of squares plates confirms MOKE imaging, i.e. large magnetic domains but a non-uniform magnetization in the samples.

Abstract: Ni, permalloy (Py: Ni - 20 at. % Fe), and Co films of 40 nm thickness are prepared on GaAs (100) single-crystal substrates at room temperature and 200 °C by magnetron sputtering. The growth behavior and crystallographic properties are studied. In early stages of film growth, metastable bcc single-crystals nucleate on the substrates for all the film materials. The crystal structure is stabilized through hetero-epitaxial growth. With increasing the thickness beyond 2 nm, the bcc structure starts to transform into fcc or hcp structure through atomic displacements parallel to the bcc {110} close-packed planes. The transformation orientation relationships are fcc {111}<10>, hcp {0001}<110> || bcc {110}<001>. The resulting Ni and Py films consist of a mixture of bcc and fcc phases, whereas the Co films involve an hcp phase in addition to the metastable bcc phase.

Abstract: Antidot arrays of various diameters were patterned in permalloy thin films to explore their magnetic behavior. Porous anodic alumina had been used as a template to fabricate magnetic films with antidot array. Permalloy had been fabricated by depositing Ni₈₀Fe₂₀ onto anodic alumina membrane templates. The film thickness was 30 and 40 nm and the diameters of antidot varied from 200 to 350 nm. The coercivity of the antidot arrays is greater than that of unpatterned films and shows weak dependence on antidot diameter. The increase of the pore diameter was suggested to enhance domain wall pinning. The coercivity reaches a maximum value for the antidot array with the smallest pore diameter and reduces to an almost constant value for the antidot arrays with larger pore diameters.

Abstract: Interlayer interactions in FeNi/Bi/FeNi trilayers have been experimentally studied. Based on the data of SQUID magnetometry and magnetic resonance investigations, it is shown that the interlayer interaction is determined by a bismuth spacer thickness and temperature. The giant magnetoresistive effect in the trilayer films has been discovered.

Abstract: In this paper, we presented a MEMS-based method of manufacturing micro fluxgate sensors. Micro-solenoid coils acting as excitation and sensing elements of the sensors were fabricated by MEMS technology and thick photoresist-based UV-lithography. Different processes were used to fabricate the magnetic cores made of different soft magnetic materials, respectively. Permalloy core was formed by electroplating, whereas gluing and chemical wet etching were adopted in the fabrication of the nanocrystalline alloy core. The two micro fluxgate sensors were characterized by a magnetic field measuring system. The experimental results showed that the micro fluxgate sensors possess high sensitivity, wide linear measuring range and low power consumption.

Abstract: Composite electromagnetic wave absorbers made of a soft magnetic material (permalloy or sendust) and polystyrene resin were investigated [1]. The volume mixture ratio of magnetic material was varied in the range from 18 vol% to 75 vol%. The composites with the low volume mixture ratio of soft magnetic material absorbed more than 99 % of electromagnetic wave power in the frequency range from 1 GHz to 10 GHz. The values of the real part
r’ of the relative complex permeability
r * for both magnetic materials were less than unity at frequencies above approximately 6 GHz as the volume mixture ratio of magnetic material increased. This result suggests the possible realization of an electromagnetic wave absorber that can operate above 10 GHz.

Abstract: The effect of mechanical stress on Barkhausen noise from 45-permalloy plate is reported for as-rolled plate and plates which are annealed at various temperatures up to 1000 K. The data are compared with data of magnetic permeability, coercive force and Vickers hardness. The Barkhausen noise energy detected has been found to increase linearly with nominal stress. The larger the annealing temperature, the less the rate of increase was observed. On the other hand, the magnetic permeability has been found to decrease linearly with nominal stress in a small stress region. Overall features are explained qualitatively by a model in which tensile stress makes the number of effective pinning sites which have appropriate activation energies for discontinuous motion of domain wall more, while annealing process makes just the number of pinning sites such as defects and grain boundaries less.

Abstract: The frequency dependences of the complex permeability μ r*, complex permittivity ε r*, and return loss were investigated for composite electromagnetic wave absorbers made of soft magnetic materials (permalloy or sendust) and polystyrene resin. For permalloy, two types of particle shape were used: grain-type or flake-type. The volume mixture ratio of magnetic materials was varied in the range from 40 % to 70 %. The values of the real part μ ’ and imaginary part μ ” of μ r * increased with increasing mixture ratio of magnetic materials. The frequency dependence of μ r * for flake-type permalloy composite was similar to that for sendust composite. All absorbers showed the absorption of electromagnetic waves in the frequency range above 1 GHz.