Investigation of the complex susceptibility of magnetic beads containing maghemite nanoparticles

Fannin, P.C.; Cohen-Tannoudji, Laetitia; Bertrand, Emanuel; Giannitsis, A. T.; Oireachtaigh, C. Mac; Bibette, Jérôme

doi:10.1016/j.jmmm.2005.07.035

Cited by 38 publications

(30 citation statements)

References 14 publications

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“…Measurements are presented in figure 7. As expected from (13), the susceptibility decreases when the magnetic field amplitude increases, which further confirms that the microparticles have a permanent magnetic moment in contrast to microparticles that only have an induced magnetic moment, which increases with the magnetic field, leading to an increase of the initial magnetic susceptibility [17,18]. The cobalt ferrite doped magnetic silica particles can gain an induced magnetic moment as well, but to see the corresponding increase of the magnetic susceptibility, the magnetic field amplitude would have to be higher than here (>1 kA m −1 ).…”

Section: Field-amplitude-dependent Complex Magnetic Susceptibilitysupporting

confidence: 81%

Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

Claesson

Erné

Bakelaar

et al. 2007

J. Phys.: Condens. Matter

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The magnetic properties of dispersions of magnetic silica microspheres have been investigated by measuring the magnetization curves and the complex magnetic susceptibility as a function of frequency and field amplitude. The silica spheres appear to have a net permanent magnetic dipole moment, even in zero field, which is increased significantly after a temporary exposure of the silica colloids to a saturating magnetic field. The magnetic properties of the microparticles in zero field are discussed in terms of the number and the orientations of the embedded nanoparticle dipoles along an easy axis of magnetization in the absence of an external field.

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Section: Field-amplitude-dependent Complex Magnetic Susceptibilitysupporting

confidence: 81%

Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

Claesson

Erné

Bakelaar

et al. 2007

J. Phys.: Condens. Matter

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“…In fact peaks in both χ and χ vs frequency are seen in ferromagnetic nanoparticulate systems where there is a broad distribution of particle sizes and thus relaxation times. When these are magnetically frozen out (or blocked) one observes a drop in the susceptibility, both real and complex, which is a function of frequency [46][47][48]. Within the Ni(TCNQ − D 4 ) 2 system we may be seeing something similar, and we may deduce that the nanograins have a broad size distribution and a peak in the susceptibility shows that the measurement is sensitive to a cluster size distribution that is within the distribution of relaxation time scales of the order of the AC susceptibility measurements.…”

Section: Parametermentioning

confidence: 99%

Separating the ferromagnetic and glassy behavior within the metal-organic magnetNi(TCNQ)2

et al. 2015

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Publisher's copyright statement:Reprinted with permission from the American Physical Society: Physical Review B 92, 184431 c 2015 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. An in-depth study of the metal-organic magnet Ni(TCNQ) 2 was conducted where the deuterated form was synthesised both to attempt to alter the magnetic properties of the material and to be advantageous in techniques such as neutron scattering and muon spectroscopy. Deuteration saw a 3 K increase in T C with magnetization and heat capacity measurements demonstrating a spin wave contribution at low temperatures confirming the 3D nature of the ferromagnetic state shown by Ni(TCNQ − D 4 ) 2 . AC susceptibility results suggest there is a glassy component associated with the magnetically ordered state, though muon spectroscopy measurements did not support the presence of a spin glass state. Instead muon spectroscopy at zero magnetic field indicated the presence of two magnetic transitions, one at 20 K and another below 6 K; the latter is likely due to the system entering a quasistatic regime, similar to what one might expect of a superspin or cluster glass. Neutron diffraction measurements further supported this by revealing very weak magnetic Bragg peaks suggesting that the magnetism may have a short coherence length and be confined to small grains or clusters. The separation of the ferromagnetic and glassy magnetic components of the material's properties suggest that this system may show promise as a metal-organic magnet which is easily modified to change its magnetic properties, providing larger grain sizes can be synthesized.

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“…This effect has been measured before in bulk samples. 23 With on chip magnetophoresis information can be obtained from individual particles, and we indeed observed distinct differences between particles. The high field susceptibility and variations herein can, for example, be interesting for biosensor applications with giant magnetoresistance ͑GMR͒ or tunnel magnetoresistance ͑TMR͒ sensors, where high frequency modulation is used to increase the signal to noise ratio.…”

Section: B High Frequency Fieldsmentioning

confidence: 52%

Analysis of individual magnetic particle motion near a chip surface

Ommering

Lamers

Nieuwenhuis

et al. 2009

Journal of Applied Physics

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We describe an analysis of the dynamics of individual superparamagnetic micro-and nanoparticles in order to quantify their magnetic properties and mobility near a chip surface. The particles are attracted to the chip surface by integrated microscopic current wires. We show that it is possible to accurately analyze particles with a diameter of about 1 m by the magnetophoretic movement between current wires because of the very high field gradients. This reveals distinct differences in volume susceptibilities of particles with the same outer diameter. Smaller particles are characterized using the technique of confined Brownian motion analysis. By capturing 300 nm particles on a current wire with surface barriers or a focused shape, the magnetization of the particles can be measured with an accuracy better than 10%.

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Investigation of the complex susceptibility of magnetic beads containing maghemite nanoparticles

Cited by 38 publications

References 14 publications

Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

Measurement of the zero-field magnetic dipole moment of magnetizable colloidal silica spheres

Separating the ferromagnetic and glassy behavior within the metal-organic magnetNi(TCNQ)2

Analysis of individual magnetic particle motion near a chip surface

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