Thermal dependence of coercivity in soft magnetic nanocrystals

Hernando, A.; Marı́n, P.; Vázquez, M.; Barandiarán, J.M.; Herzer, G.

doi:10.1103/physrevb.58.366

Cited by 99 publications

(52 citation statements)

References 15 publications

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“…Under the assumption that a polycrystalline nanoparticle of a small diameter, D < D c , has strictly uniform magnetization, it is possible to determine 27,28 the direction of the effective easy anisotropy axis of the particle and to calculate the value of the corresponding effective anisotropy constant. In agreement with the random anisotropy model, [29][30][31][32] the latter turns out to be much smaller than the original value of uniaxial anisotropy constant of single-crystal hcp cobalt. This is due to averaging of the anisotropic interactions in a polycrystalline nanoparticle.…”

Section: Resultssupporting

confidence: 57%

“…The well -known random anisotropy model 29 is widely used [30][31][32] to describe qualitatively the magnetic properties of nanocrystalline ferromagnetic media. This approach has also been utilized to estimate the effective magnetic anisotropy constant of polycrystalline magnetic nanoparticles, 27,28 assuming that a sufficiently small magnetic nanoparticle should be nearly uniformly magnetized due to ordering influence of the exchange interaction, which prevails at small particle sizes.…”

Section: Discussionmentioning

confidence: 99%

“…For such polycrystalline nanoparticles an approximate estimate of the effective magnetic anisotropy constant was made 27,28 based on the random anisotropy model. [29][30][31][32] Unfortunately, to date the statistics of the single-crystal granules in polycrystalline nanoparticles is still poorly investigated experimentally. In this paper, to investigate the magnetic properties of polycrystalline nanoparticles we adopt a simple model where the particle volume is randomly decomposed into N g = 4 -16 crystallites of various sizes.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic properties of polycrystalline cobalt nanoparticles

et al. 2017

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The energy diagram of stationary magnetization states existing in polycrystalline cobalt nanoparticles in the range of diameters 20 ≤ D ≤ 60 nm has been calculated by means of numerical simulation. It is shown that in polycrystalline cobalt nanoparticles in the range of diameters D ≥ 32 nm only vortex states with low average magnetization are present, whereas mostly quasi-uniform states are realized in nanoparticles with diameter D ≤ 24 nm. Thus, the effective single-domain diameter of polycrystalline cobalt nanoparticles is estimated to be Dc = 24 nm. It is approximately two times smaller than the actual single-domain diameter of monocrystalline cobalt nanoparticle, Dc0 = 45 nm. The hysteresis loops of a dilute assembly of polycrystalline cobalt nanoparticles in the range of diameters D ≤ Dc are characterized by a coercive force that is approximately 2.5 times less compared with that of the randomly oriented assembly of monocrystalline cobalt nanoparticles.

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Section: Resultssupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Magnetic properties of polycrystalline cobalt nanoparticles

et al. 2017

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“…Sulitanu has reported that Ni-W alloy thin films with perpendicular magnetic anisotropy can be obtained due to the binary phase structure with an isolated columnar nanocrystalline phase surrounded by an amorphous-like phase (4% < R W depo < 5%) [27]. The present report has also estimated that the perpendicular magnetic anisotropy in the alloy films arises [28].…”

Section: Magnetic Properties Of Electrodeposited Ni-w Alloy Nanowiressupporting

confidence: 60%

Isotropic magnetization response of electrodeposited nanocrystalline Ni–W alloy nanowire arrays

2013

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Isotropic magnetization response was demonstrated in electrodeposited nanocrystalline Ni-15%W alloy nanowire arrays, which can be applied to nanoscale magnetic field sensors. The Ni-W alloy nanowire arrays were electrochemically synthesized on a nanochannel template electrode from an aqueous electrolytic solution. X-ray and electron diffraction patterns revealed that Ni-15%W alloy deposits were composed of ultrafine crystal grains with a supersaturated solid solution phase. The magnetization of the Ni-15%W alloy thin films reached saturation at around 2.5 kOe in a perpendicular direction to the film plane, whereas the pure Ni thin films hardly magnetized in the perpendicular direction. On the contrary, Ni-15%W alloy nanowire arrays were easily magnetized, and reach saturation at around 1.0 kOe, even in a perpendicular direction to the array film plane that corresponds to the long axis direction of the alloy nanowires.

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“…7 However, in two-phase systems, consisting of nanocrystallites randomly distributed in a magnetic amorphous matrix, the increase of coercivity with temperature has been observed close to the transition temperature of the soft amorphous phase. [8][9][10] Also in other materials, controversial mechanisms 11,12 and anomalies [3][4][5][6] of the temperature dependence of the coercivity have been reported so far. From a fundamental point of view, it is important to understand how the anisotropy can be enhanced with increasing temperature.…”

mentioning

confidence: 99%

Origin of the anomalous temperature dependence of coercivity in soft ferromagnets

Moubah

Ahlberg

Zamani

et al. 2014

Journal of Applied Physics

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We report on the origin of the anomalous temperature dependence of coercivity observed in some soft ferromagnets by studying the magnetic and electronic properties of FeZr films doped using ion implantation by H, He, B, C, and N. The anomalous increase of the coercivity with temperature was observed only in the C- and B-doped samples. Using x-ray photoelectron spectroscopy, we show that the anomalous behavior of the coercivity coincides with the occurrence of an electron charge transfer for those implanted samples. The origin of the anomaly is discussed in terms of (i) magnetic softness, (ii) nature of the Fe-C and -B covalent bonds, and (iii) large charge transfer

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Thermal dependence of coercivity in soft magnetic nanocrystals

Cited by 99 publications

References 15 publications

Magnetic properties of polycrystalline cobalt nanoparticles

Magnetic properties of polycrystalline cobalt nanoparticles

Isotropic magnetization response of electrodeposited nanocrystalline Ni–W alloy nanowire arrays

Origin of the anomalous temperature dependence of coercivity in soft ferromagnets

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