Coercivity and exchange bias in size reduced iron obtained through chemical reduction

Sivaranjani, K.; Jacob, G. Antilen; Joseyphus, R. Justin

doi:10.1016/j.jmmm.2020.167228

Cited by 12 publications

(5 citation statements)

References 56 publications

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“…The differences in the coercive fields may be attributed to a slightly increased surface roughness of the PAN film as compared to the wafer, as was reported before for Co thin films [27]. This may be interesting for further examinations of thin films on such uneven substrates, since the exchange bias-a unidirectional anisotropy occurring in coupled ferromagnetic/antiferromagnetic systems, such as the here examined Co/CoO at lower temperatures [28]-may also be increased with increasing roughness [29]. The unusual shapes of the hysteresis loops, including clearly visible asymmetries, have to be discussed.…”

Section: Methodssupporting

confidence: 68%

MOKE and MFM on magnetically coated nanofiber mats: Transferring well‐known methods to uncommon samples

et al. 2023

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The hysteresis loops of magnetic samples can be measured by the magneto-optical Kerr effect (MOKE), while magnetic force microscopy (MFM) is used to depict domain walls or spatially resolved magnetization orientation in magnetic nanostructures or thin films. Both methods are commonly applied on thin films with a perfectly flat surface or on nanostructures. Here, we report MOKE and MFM measurements on a new class of magnetic materials, namely electrospun mats of randomly oriented nanofibers which influence the 30 nm Co coating layer, proving especially the MOKE method utilizable for rough surfaces. Possible interpretations of these first MOKE measurements on highly randomly structured magnetic layers are given.

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Section: Methodssupporting

confidence: 68%

MOKE and MFM on magnetically coated nanofiber mats: Transferring well‐known methods to uncommon samples

et al. 2023

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“…Size‐reduced Fe nanoparticles (50 and 20 nm) were obtained using chloroplatinic acid (H 2 PtCl 6 ⋅6H 2 O) as a heterogenous nucleating agent with EG as the reducing medium as reported elsewhere. [ 100 ] Bulk Fe wires of varying lengths were used to study the effect of demagnetization on the length of the samples. The samples were named after the polyol used for the synthesis or termed after the average size obtained from electron microscopy.…”

Section: Methodsmentioning

confidence: 99%

“…Fe particles of varying sizes were synthesized using EG, PG, Gly, and DiMG as the reducing media availing the instant chemical reduction process exclusively developed by the authors. [90,[96][97][98][99][100] Magnetite nanoparticles were obtained in terminal polyols, such as 1,3-propanediol (t-PG) and 1,4-butanediol (t-BG), under similar experimental conditions. In a typical reaction, the polyols were heated up to 170 °C followed by the stochiometric addition of ferrous chloride tetrahydrate salt and NaOH pellets within a time interval of 5 s. The black precipitate obtained after the reaction, that lasted not more than 5 min, was cooled down using methanol and the particles were magnetically separated.…”

Section: Methodsmentioning

confidence: 99%

Comprehensive Law‐of‐Approach‐to‐Saturation for the Determination of Magnetic Anisotropy in Soft Magnetic Materials

Sivaranjani

Jacob

Joseyphus

2022

Physica Status Solidi (b)

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Magnetocrystalline anisotropy is a crucial parameter that determines the suitability of magnetic material in a wide range of emerging applications. The law‐of‐approach‐to‐saturation (LAS), utilized to obtain the magnetocrystalline anisotropy from hysteresis loops, is not satisfactory for materials with cubic anisotropy as they are two orders higher than the bulk value. Herein, a modified formulation to LAS is presented, where the reduction in effective magnetic anisotropy (K) values due to Fe oxide phases in Fe particles over wide size ranges is accounted. The value of K decreases from 4.2 × 104 J m−3 for the Fe particles of average size 210 nm to 1.2 × 104 J m−3 for the 20 nm particles due to the increase in the iron oxide fraction with size reduction. The effective magnetic anisotropy obtained from the modified LAS has been validated from the ferromagnetic resonance studies for particles of the smallest size.

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“…[ 13,36,38,39 ] The NaOH pellets were introduced immediately within 2 s interval that facilitates the reduction of Fe. [ 13,40 ] An X‐ray diffraction analysis confirms the fcc phase for the Ni 60 Cu 39 Fe 1 and Ni 60 Cu 38 Fe 2 samples, as shown in Figure . The lattice parameters for the Ni 60 Cu 39 Fe 1 and Ni 60 Cu 38 Fe 2 samples are 3.540(2) and 3.563(2) Å, respectively.…”

Section: Resultsmentioning

confidence: 70%

Enhanced Curie Temperature and Critical Exponents of Fe‐Substituted NiCu Alloy

Jacob

Joseyphus

2021

Physica Status Solidi (a)

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The magnetic moment and the Curie temperature of the NiCu alloy decrease to a large extent with Cu. A Ni60Cu40 alloy with Fe substitutions up to 2 at% using a polyol‐mediated synthesis process resulting in enhanced magnetic properties is obtained. The Ni60Cu39Fe1 and Ni60Cu38Fe2 alloys show fcc phase with the Curie temperatures of 237 and 266 K, respectively. The room temperature magnetization measurement shows paramagnetic behavior, whereas, at 15 K, the 1 at% Fe‐substituted alloy exhibits a saturation magnetization of 20 emu g−1 that increases by 25% with 2 at% Fe. The positive slope in the Arrott plot confirms the second‐order phase transition in the alloys. The maximum magnetic entropy change (MCE) is observed as 0.101 J kg−1 K−1 for the Ni60Cu39Fe1 alloy with the peak temperature of 238 K in an applied magnetic field of 0.5 T. The critical exponent (β) calculated using the MCE method is in the range of 0.576(3)–0.587(3) for the alloys, whereas the values obtained using the Kouvel‐Fisher (KF) method are 0.523(3)–0.565(2). The extracted β values are slightly greater than the mean‐field model suggesting clustering behavior in the alloys.

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Coercivity and exchange bias in size reduced iron obtained through chemical reduction

Cited by 12 publications

References 56 publications

MOKE and MFM on magnetically coated nanofiber mats: Transferring well‐known methods to uncommon samples

MOKE and MFM on magnetically coated nanofiber mats: Transferring well‐known methods to uncommon samples

Comprehensive Law‐of‐Approach‐to‐Saturation for the Determination of Magnetic Anisotropy in Soft Magnetic Materials

Enhanced Curie Temperature and Critical Exponents of Fe‐Substituted NiCu Alloy

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