Thermomagnetically patterned micromagnets

Dumas-Bouchiat, Frédéric; Zanini, Luiz-Fernando; Kustov, Mikhail; Dempsey, Nora; Гречишкин, Р. М.; Hasselbach, K.; Orlianges, Jean‐Christophe; Champeaux, Corinne; Catherinot, A.; Givord, D.

doi:10.1063/1.3341190

Cited by 103 publications

(68 citation statements)

References 18 publications

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“…The external field of -0.1 T represents a typical value that could be applied on the magnetic film by a driving coil in a device, while the external field of -0.5 T represents a typical value that the film could feel in the vicinity of a bulk magnet, and corresponds to the field value used during thermomagnetic patterning. 8 For the thermal cycling measurements, the films were first saturated at 300K and then the film was cycled 100 times between 293K and a given set temperature (323K or 343K) under zero field and the remanence was measured at the upper and lower temperatures of each cycle. Finally, room temperature hysteresis loops were measured on all samples following the above detailed measurements.…”

Section: Experiments Proceduresmentioning

confidence: 99%

“…2,7 Hard magnetic films may be exposed to elevated temperatures either in the course of fabrication (e.g. during thermomagnetic patterning (TMP) to produce multi-pole structures, 8 or during wafer bonding or device packaging steps) or during device use, and therefore it is important to know the thermal resistance of the magnetic film. Most reports on the temperature dependent properties of NdFeB-based magnets concern samples with elemental additions (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

et al. 2018

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Hard magnetic films used in magnetic micro-systems may be exposed to elevated temperatures during film and system fabrication and also during use of the micro-system. In this work, we studied the influence of temperature on the magnetic properties of 10 μm thick out-of-plane textured NdFeB films fabricated by high rate triode sputtering. Out-of-plane hysteresis loops were measured in the range 300K – 650K to establish the temperature dependence of coercivity, magnetization at 7 T and remanent magnetization. Thermal demagnetization was measured and magnetization losses were recorded from 350K in films heated under zero or low (-0.1 T) external field and from 325 K for films heated under an external field of -0.5 T. The effect of thermal cycling under zero field on the remanent magnetization was also studied and it was found that cycling between room temperature and 323 K did not lead to any significant loss in remanence at room temperature, while a 4% drop is recorded when the sample is cycled between RT and 343K. Measurement of hysteresis loops at room temperature following exposure to elevated temperatures reveals that while remanent magnetisation is practically recovered in all cases, irreversible losses in coercivity occur (6.7 % following heating to 650K, and 1.3 % following heating to 343K). The relevance of these results is discussed in terms of system fabrication and use.

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Section: Experiments Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

et al. 2018

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“…ilm magnets, such as a Nd-Fe-B, Sm-Co or Fe-Pt film, were prepared by a lot of researchers using several deposition methods [1]- [18]. Our group has focused on a PLD method to obtain isotropic Nd-Fe-B thick-film magnets with the maximum thickness up to 1250 μm on metal substrates (Ta, Fe, W) under the relatively high deposition rate of several-ten-microns per hour and applied the films to several miniaturized electronic devices [19]- [21].…”

Section: Introductionmentioning

confidence: 99%

PLD-Fabricated Isotropic Pr–Fe–B Film Magnets Deposited on Glass Substrates

et al. 2017

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“…Micro-patterning of such films, using topographic (lithography) 19 or thermo-magnetic (temperature control of magnetization reversal) 20 approaches, produces micron-sized permanent magnets characterized by stray magnetic field gradients as high as 10 6 T/m. 21 The flat surface of thermo-magnetically patterned films facilitates their integration into microfluidic devices, and they have been used to trap magnetic particles (SiO 2 and polystyrene particles containing magnetic nanoparticles) within such a device.…”

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confidence: 99%

Microfluidic immunomagnetic cell separation using integrated permanent micromagnets

et al. 2013

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In this paper, we demonstrate the possibility to trap and sort labeled cells under flow conditions using a microfluidic device with an integrated flat micro-patterned hard magnetic film. The proposed technique is illustrated using a cell suspension containing a mixture of Jurkat cells and HEK (Human Embryonic Kidney) 293 cells. Prior to sorting experiments, the Jurkat cells were specifically labeled with immunomagnetic nanoparticles, while the HEK 293 cells were unlabeled. Droplet-based experiments demonstrated that the Jurkat cells were attracted to regions of maximum stray field flux density while the HEK 293 cells settled in random positions. When the mixture was passed through a polydimethylsiloxane (PDMS) microfluidic channel containing integrated micromagnets, the labeled Jurkat cells were selectively trapped under fluid flow, while the HEK cells were eluted towards the device outlet. Increasing the flow rate produced a second eluate much enriched in Jurkat cells, as revealed by flow cytometry. The separation efficiency of this biocompatible, compact micro-fluidic separation chamber was compared with that obtained using two commercial magnetic cell separation kits.

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Thermomagnetically patterned micromagnets

Cited by 103 publications

References 18 publications

Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

PLD-Fabricated Isotropic Pr–Fe–B Film Magnets Deposited on Glass Substrates

Microfluidic immunomagnetic cell separation using integrated permanent micromagnets

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