Influence of surface on the effective magnetic fields in α-Fe2O3 and FeBO3

Kamzin, A. S.; Stahl, B.; Gellert, R.; Müller, Michael; Kankeleit, E.; Vcherashnii, D. B.

doi:10.1134/1.1309453

Cited by 1 publication

(2 citation statements)

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“…Usually, reduction of nanoparticles magnetization compared to that of bulk can occur for a variety of reasons. Often it is caused by oxidation which results in reduction of a core or otherwise it is caused by existence of thin layers of crystallites with the noncollinear magnetic moments on the surface [31][32][33][34]. Other possible explanations involve existence of thin surface paramagnetic ("dead") layers or presence of very small superparamagnetic particles [32].…”

Section: Squid Magnetometrymentioning

confidence: 99%

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Structure and size dependence of the magnetic properties of Ni@C nanocomposites

Manukyan

Elsukova

Mirzakhanyan

et al. 2018

Journal of Magnetism and Magnetic Materials

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Carbon-coated nickel (Ni) nanoparticles, Ni@C nanocomposites, have been synthesized using solid-state pyrolysis of nickel phthalocyanine and metal-free phthalocyanine (NiPc) x •(H 2 Pc) 1-x solid solutions, 0 ≤ x ≤ 1. The Ni concentrations in carbon matrix (c Ni ) of the prepared samples continuously varied in the range of 0-3at.% (0-12wt.%). The average nanoparticle size varied within 4-40 nm range. All samples containing single domain Ni nanoparticles exhibit both ferromagnetic and superparamagnetic properties because of the wide range of size distribution. An abrupt drop of saturation magnetization has been observed with decrease in size of Ni nanoparticles from 40 nm to 12 nm. Nearly linear dependence of saturation magnetization on the nanoparticle surface/volume ratio can be interpreted as a result of contact interaction between Ni nanoparticles and the carbon matrix which provides an electron transfer from carbon matrix to nickel. However, further reductions in nanoparticle size increase magnetization growth of which can apparently contribute to the emergence of the giant paramagnetism due to large orbital moments of conductive electrons. The size effects and surface magnetic anisotropy in Ni@C nanocomposites are revealed in the measurements of coercive field, zero-field cooling (ZFC) susceptibility, blocking temperatures and ferromagnetic resonance spectra. Concentration dependencies of ferromagnetic and electron paramagnetic resonance parameters in Ni@C nanocomposites have also been investigated and their peculiarities highlighted. A correlation between concentration dependencies of FMR and SQUID magnetometry parameters, namely between the g-factor curvesg e f f , the resonance linewidth -∆H FMR and coercive field -H c , have been observed.

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Section: Squid Magnetometrymentioning

confidence: 99%

“…The possible reasons of magnetization reduction with decrease in nanoparticle size are discussed in Refs. [27,[31][32][33][34][35][36]. In current work a drop of saturation magnetization in Ni@C nanocomposites has been described.…”

Section: Introductionmentioning

confidence: 99%