Magnetic relaxation and correlating effective magnetic moment with particle size distribution in maghemite nanoparticles

Pisane, Kelly L.; Despeaux, Emily; Seehra, M. S.

doi:10.1016/j.jmmm.2015.02.038

Cited by 56 publications

(43 citation statements)

References 38 publications

(84 reference statements)

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“…We have also plotted the T bif in Fig. 5(d) as a function of growth pressure; here T bif is the temperature at which the FC curve bifurcates from the ZFC curve 44 . Figure 6(a) shows the FC curves measured in applied H = 1 kOe; it is evident that all the thin films synthesized at different growth pressures exhibit ferromagnetic behavior (as also confirmed in the next figure) since as in ferromagnets, M gradually decreases with increase of temperature up to the Curie temperature (300-345 K here) ( Fig.…”

Section: Magnetic Properties Of Lsmo Thin Filmsmentioning

confidence: 99%

Effects of Oxygen Modification on the Structural and Magnetic Properties of Highly Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films

Kumari

Mottaghi

Huang

et al. 2020

Sci Rep

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a strong semi-metallic ferromagnet having robust spin polarization and magnetic transition temperature (T c) well above 300 K, has attracted significant attention as a possible candidate for a wide range of memory, spintronic, and multifunctional devices. Since varying the oxygen partial pressure during growth is likely to change the structural and other physical functionalities of La 0.7 Sr 0.3 MnO 3 (LSMO) films, here we report detailed investigations on structure, along with magnetic behavior of LSMO films with same thickness (~30 nm) but synthesized at various oxygen partial pressures: 10, 30, 50, 100, 150, 200 and 250 mTorr. The observation of only (00 l) reflections without any secondary peaks in the XRD patterns confirms the high-quality synthesis of the above-mentioned films. Surface morphology of the films reveals that these films are very smooth with low roughness, the thin films synthesized at 150 mTorr having the lowest average roughness. The increasing of magnetic T c and sharpness of the magnetic phase transitions with increasing oxygen growth pressure suggests that by decreasing the oxygen growth pressure leads to oxygen deficiencies in grown films which induce oxygen inhomogeneity. Thin films grown at 150 mTorr exhibits the highest magnetization with T C = 340 K as these thin films possess the lowest roughness and might exhibit lowest oxygen vacancies and defects. Interpretation and significance of these results in the 30 nm LSMO thin films prepared at different oxygen growth pressures are also presented, along with the existence and growth pressure dependence of negative remanent magnetization (NRM) of the above-mentioned thin films. The miniaturization of devices to increase speed and reduce the cost of materials is an ongoing need for many current and potential magnetic technologies such as spintronics, highly dense non-volatile memory, spin-caloritronics, and different multifunctional micro and nanoscale devices 1-5. Among important materials for device applications are room temperature ferromagnetic oxides such as the manganites, La 1−x Sr x MnO 3 , since their properties can be tuned using a number of degrees of freedom including charge, spin, orbital, and magnetic ordering phenomena 6,7. They are also excellent candidates for novel engineered nanostructures as they exhibit colossal magnetoresistance (CMR) effect which has been used for different multifunctional applications 8-10. La 1− x Sr x MnO 3 also shows CMR phenomena under smaller external magnetic fields compared to the other manganites and strongly correlated materials 11,12. Among the La 1−x Sr x MnO 3 manganites, the optimized stoichiometry La 0.7 Sr 0.3 MnO 3 (LSMO) is one of the most prominent members with outstanding magnetic and magneto-transport properties. Compared to other typical magnetic oxides, LSMO exhibits semi-metallic behavior, outstanding ferromagnetism, high Fermi-level spin polarization, with a bulk magnetic ordering temperature, T C (= 370 K) well above room temperature 13,14. Also, the spin polarization of LSMO ...

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Section: Magnetic Properties Of Lsmo Thin Filmsmentioning

confidence: 99%

Effects of Oxygen Modification on the Structural and Magnetic Properties of Highly Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films

Kumari

Mottaghi

Huang

et al. 2020

Sci Rep

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“…The particle dimensions were evaluated by HR-SEM measurements, where a drop of the nanoparticle solution was spread onto a Carbon Film 300 Mesh Cu. The size distribution for all NPs was fitted to the log-normal distribution with Do = median particle diameter and D = width of the distribution with average particle diameter <D>, and standard deviation [33]. Spherical Ag NPs with an average particle diameter <D> of 12.7 ± 1.2 nm (Figure 3) were found.…”

Section: Resultsmentioning

confidence: 99%

Stabilization of Silver Nanoparticles with a Dithiocarbamate Ligand and Formation of Nanocomposites by Combination with Polythiophene Derivative Nanoparticles

Reynoso-García

Güizado-Rodrı́guez

Barba

et al. 2018

Advances in Condensed Matter Physics

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Spherical morphology for silver nanoparticles (Ag NPs) stabilized with dithiocarbamate (DTC) by reducing silver nitrate with sodium borohydride was obtained, while the addition of sodium citrate and hydrogen peroxide allowed the formation of silver nanotriangles (Ag NTs). Solutions of bright yellow and blue colors characteristic of both morphologies were observed. UV-vis optical analysis of NPs stabilized with DTC showed a plasmonic absorption band at 393 nm characteristic for spherical morphology, while two bands were observed at 332 nm and 762 nm, and a shoulder around 500 nm for the triangular morphology; with these spectra each morphology was confirmed. In these spectra an absorption band between 250 and 260 nm confirms the presence of DTC ligand. The stability of the NPs was achieved using an 8.69 × 10-3 mM solution of 4-(ethylaminodithiocarbamate) methylpyridine di-n-butyltin (IV) through a transmetallation reaction. Silver nanoparticles (Ag NPs) with spherical morphology of average diameter of 12.7 ± 1.2 nm and triangular morphology with 28.9 ± 0.8 nm for each side of the triangles were analyzed by high resolution scanning electron microscopy (HR-SEM). UV-vis spectra also showed the stability of NPs with DTC for more than three months. A copolymer derived of 3-hexylthiophene with (E)-2-(ethyl(4-((4-nitrophenyl) diazenyl) phenyl) amino) ethyl 2-(thiophen-3-yl) acetate (PA) was tested to get polymer NPs by reprecipitation method using THF/water systems. PA Polymer NPs having average diameter of 9.0 ± 1.7 nm were found. By quick and easy procedure, the formation of nanocomposite (NC) of spherical Ag NPs and PA polymer NPs was reached. This NC could be used as imaging agent, electrochemical biosensor, and photonic and optoelectronic device materials.

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“…Indeed, previous experimental studies have shown that the distribution of F particle sizes plays a key role for the understanding of ferromagnetic nanoparticle behavior. 26,[52][53][54] In the following, a lognormal distribution of particle diameters is used with a mean diameter < d >= 8.29 nm and standard deviation σ sd = 2.99 nm. It should be noted that previous studies have shown that lognormal distributions are often observed in experimental systems.…”

Section: B Size-distributed Fm Particlesmentioning

confidence: 99%

“…It should be noted that previous studies have shown that lognormal distributions are often observed in experimental systems. 22,29,52,54,55 The nanoparticles are assumed to be all aligned along their easy axis. Figure 8 (left axis, round red symbols) shows the normalized particle size distribution D in the range of (4 to 25) nm, for 100 discrete d values.…”

Section: B Size-distributed Fm Particlesmentioning

confidence: 99%

Thermal simulation of magnetization reversals for size-distributed assemblies of core-shell exchange biased nanoparticles

Jay

Pogossian

Youssef

et al. 2016

Journal of Applied Physics

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A temperature dependent coherent magnetization reversal model is proposed for size-distributed assemblies of ferromagnetic nanoparticles and ferromagnetic-antiferromagnetic core-shell nanoparticles. The nanoparticles are assumed to be of uniaxial anisotropy and all aligned along their easy axis. The thermal dependence is included by considering thermal fluctuations, implemented via the Néel-Arrhenius theory. Thermal and angular dependence of magnetization reversal loops, coercive field and exchange-bias field are obtained, showing that F-AF size-distributed exchangecoupled nanoparticles exhibit temperature-dependent asymmetric magnetization reversal. Also, non-monotonic evolutions of He and Hc with T are demonstrated. The angular dependence of Hc with T exhibits a complex behavior, with the presence of an apex, whose position and amplitude are strongly T dependent. The angular dependence of He with T exhibits complex behaviors, which depends on the AF anisotropy and exchange coupling. The resulting angular behavior demonstrates the key role of the size distribution and temperature in the magnetic response of nanoparticles.

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Magnetic relaxation and correlating effective magnetic moment with particle size distribution in maghemite nanoparticles

Abstract: The role of particle size distribution inherently present in magnetic nanoparticles (NPs) is examined in considerable detail in relation to the measured magnetic properties of oleic acid-

Cited by 56 publications

References 38 publications

Effects of Oxygen Modification on the Structural and Magnetic Properties of Highly Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films

Effects of Oxygen Modification on the Structural and Magnetic Properties of Highly Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films

Stabilization of Silver Nanoparticles with a Dithiocarbamate Ligand and Formation of Nanocomposites by Combination with Polythiophene Derivative Nanoparticles

Thermal simulation of magnetization reversals for size-distributed assemblies of core-shell exchange biased nanoparticles

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