Thick-film permanent magnets by membrane electrodeposition

Rhen, Fernando M.F.; Backen, E.; Coey, J. M. D.

doi:10.1063/1.1923587

Cited by 68 publications

(42 citation statements)

References 19 publications

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“…The electrolyte contained 0.10 M cobalt sulfamate, 0.04 M diamminedinitritoplatinum, and 0.10 M diammonium hydrogen citrate. 5 The pH was adjusted to 6.5-6.7 using sodium hydroxide. A three-electrode cell with an Ag/AgCl ͑sat KCl͒ reference electrode and a Pt wire counter electrode, with an area of 0.95 cm 2 was used.…”

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confidence: 99%

Influence of an Au capping layer on the magnetic properties of CoPt nanowires

Byrne

Monzón

Stamenov

et al. 2011

Applied Physics Letters

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Equiatomic CoPt nanowires with a gold cap layer have been fabricated by electrochemical template synthesis. Au improves the structural and magnetic properties of the L1 0 ordered CoPt, leading to coercivities of up to 1.43 T. The anisotropy constant K 1 was estimated as 3.9͑9͒ MJ m −3 from the approach to saturation, and four effective anisotropy constants were determined from analysis of torque curves in a 14 T field. Multisegmented magnetic nanowires are produced using gold interlayers. © 2011 American Institute of Physics. ͓doi:10.1063/1.3601748͔ Binary Co-Pt alloys with an L1 0 structure have been widely investigated for high density magnetic recording media, microelectromechanical systems, giant magnetoresistance sensors, and bio-sensors. When their composition is close to equiatomic, CoPt alloys undergo a phase transformation from a disordered face-centered cubic ͑fcc͒ structure to the ordered face-centered tetragonal ͑fct͒, L1 0 structure on annealing below 825°C. 1 Magnetocrystalline anisotropy is then Ϸ5 MJ m −3 . Permanent magnets with a large coercivity and a high magnetization ͑810 kA m −1 ͒ can be produced. 2,3 Electrodeposition of Co-Pt films is a simple alternative to sputter deposition. Electrochemical template synthesis in anodisc aluminum oxide membranes also enables the fabrication of CoPt nanowires with controllable dimensions. 4 A postdeposition annealing process is required to obtain the L1 0 ordered phase. Rhen et al. 5 achieved a coercivity of 1.30 T for CoPt nanowires while Liu et al. 6 obtained coercive fields of 1.35 T and 0.45 T parallel and perpendicular to the wire axis, respectively. Their method involved fabricating Co/Pt multilayered nanowires and subsequent annealing which produced a mixture of fcc and fct phases due to incomplete mixing of the Co and Pt segments.Previous work has shown that the addition of a third, nonmagnetic element, such as Sn, Pb, Sb, Bi, Cu, Ag, and Au can reduce the annealing temperature required to obtain wellordered L1 0 CoPt films. 7-9 Gold combines unique optical, electrical, and chemical properties with biocompatibility. 10,11 The effect of an Au spacer layer on the magnetic properties of CoPt films prepared by sputtering has been examined. [12][13][14] The diffusion of Au into CoPt improves the phase transformation from disordered fcc to ordered fct. Yuan et al. 14 achieved a coercive field of 1.20 T in CoPt/Au thin films. Min et al. 15 showed an enhancement in coercivity and improved squareness in the hysteresis curves of Au doped CoPt nanowires, and they found that CoPt nanowires with larger diameter wires ͑200 nm͒ formed a tetragonal phase but 50 nm diameter formed a cubic phase with reduced coercivity contrary to the results of Shamaila et al. 16 Here, equiatomic CoPt nanowires have been fabricated by electrochemical template synthesis. An Au cap layer was then deposited above CoPt wires using a dual bath technique. Postdeposition annealing produces L1 0 CoPt/Au nanowires. Structural and magnetic properties of these wires are presented and a ...

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Influence of an Au capping layer on the magnetic properties of CoPt nanowires

Byrne

Monzón

Stamenov

et al. 2011

Applied Physics Letters

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“…The volume of the device is approximately 30 mm 3 with a predicted maximum power of 85 W. In this study, the mechanical and electrical characteristics of two designs of power generator are compared. The twodimensional ͑2D͒ finite element analysis ͑FEA͒ has been carried out to predict the voltage and power generated by the device using the magnetic properties of electroplated Co 50 Pt 50 fct phase, with the highest coercivity of 1.3 T in electroplated films reported in literature, 15 for a frequency typically present in industrial machinery.…”

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“…A silicon cantilever beam ͑0.3ϫ 1.2ϫ 0.5 mm 3 ͒ connects the paddle to the frame. This coil arrangement is bonded between two sets of 1 mm wide and 150 m thick Co 50 Pt 50 fct phase hard magnets, 15 electroplated on separate silicon wafers ͑Fig. 1͒.…”

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Vibration based electromagnetic micropower generator on silicon

Kulkarni¹,

Roy²,

O’Donnell³

et al. 2006

Journal of Applied Physics

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This paper discusses the theory, design and simulation of electromagnetic micropower generators with electroplated micromagnets. The power generators are fabricated using standard microelectromechanical system processing techniques. Electromagnetic two-dimensional finite element anlysis simulations are used to determine voltage and power that can be generated from different designs. This paper reports a maximum voltage and power of 55 mV and 70 W for the first design, incorporating microfabricated two-layer Cu coils on a Si paddle vibrating between two sets of oppositely polarized electroplated Co 50 Pt 50 face centered tetragonal phase hard magnets. A peak voltage and power of 950 mV and 85 W are obtained for the second design, which includes electroplated Ni 45 Fe 55 as a soft magnetic layer underneath the hard magnets. The volume of the device is about 30 mm 3 .

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“…If we choose cobalt platinum (Co-Pt) based permanent magnetic material for purpose of monolithic integration [76,77], then the height of the permanent magnet could not exceed 100 μm.…”

Section: Design Of the New Em Energy Harvestermentioning

confidence: 99%

“…Input parameters a) and b) for the permanent magnet are based on properties of the CMOS post-processed Co-Pt material [76,77]. The neodymiumiron-boron (Nd-Fe-B) based permanent magnets offer a higher residual magnetization (1 tesla) [81], but only for a higher process temperature (500 ºC) [82], not allowing CMOS post-processing.…”

Section: Modelmentioning

confidence: 99%

Solar cells on CMOS chips as energy harvesters : integration and CMOS compatibility

Lu¹

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Thick-film permanent magnets by membrane electrodeposition

Cited by 68 publications

References 19 publications

Influence of an Au capping layer on the magnetic properties of CoPt nanowires

Influence of an Au capping layer on the magnetic properties of CoPt nanowires

Vibration based electromagnetic micropower generator on silicon

Solar cells on CMOS chips as energy harvesters : integration and CMOS compatibility

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