Role of the surface effects and interparticle magnetic interactions in the temperature evolution of magnetic resonance spectra of ferrihydrite nanoparticle ensembles

Описание

Тип публикации: статья из журнала

Год издания: 2022

Идентификатор DOI: 10.1016/j.rinp.2022.105340

Ключевые слова: ferrihydrite nanoparticles, ferromagnetic resonance, interparticle magnetic interactions, superparamagnetism

Аннотация: Ferrihydrite is characterized by the antiferromagnetic ordering and, in ferrihydrite nanoparticles, as in nanoparticles of any antiferromagnetic material, an uncompensated magnetic moment is formed. We report on the investigations of ferrihydrite powder systems with an average particle size of ∼ 2.5 nm obtained (i) as a product of Показать полностьюthe vital activity of bacteria (sample FH-bact) and (ii) by a chemical method (sample FH-chem). In the first approximation, these samples can be considered to be identical. However, in sample FH-chem, particles contact directly, while in sample FH-bact, they have organic shells; therefore, the interparticle magnetic interactions in these samples have different degrees. The main goal of this work has been to establish the effects of the interparticle magnetic interactions and individual characteristics of ferrihydrite nanoparticles on ferromagnetic resonance (FMR) spectra. The FMR spectra have been measured at different (9.4–75 GHz) frequencies in a wide temperature range. It has been found that, at low temperatures, the field-frequency dependence ν(HR) of the investigated systems has a gap ν/γ = HR + HA, where HR is the resonance field and HA is the induced anisotropy, which decreases with increasing temperature. To estimate a degree of the effect of interparticle interactions on the results obtained and to correctly determine the temperature range of the superparamagnetic (or blocked) state, the static magnetic measurement and Mössbauer spectroscopy data have been obtained and analyzed. It has been shown that the most striking feature of the FMR spectra - a gap in the field-frequency dependences - is a manifestation of individual characteristics of ferrihydrite nanoparticles. The induced anisotropy is caused by freezing of a subsystem of surface spins and its coupling with the particle core, which is observed in both samples at a temperature of ∼80 K. The temperature range (below 80 K) in which the gap exists corresponds to the blocked state in the FMR technique. In sample FH-bact, the ratio between the FMR parameters HA and linewidth ΔH obeys the standard expression HA ∼ (ΔH)3. In sample FH-chem, however, the interparticle magnetic interactions dramatically affect the behavior of parameters of the FMR spectra, which change nonmonotonically upon temperature variation. This fact is attributed to the collective freezing of the magnetic moments of particles under the conditions of sufficiently strong interactions, which follows from the temperature dependence of the particle magnetic moment relaxation time determined from the Mössbauer spectroscopy and static magnetometry data obtained in weak magnetic fields. © 2022 The Author(s)

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Издание

Журнал: Results in Physics

Выпуск журнала: Vol. 35

Номера страниц: 105340

ISSN журнала: 22113797

Издатель: Elsevier B.V.

Персоны

  • Balaev D.A. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation, Siberian Federal University, Svobodniy 79, Krasnoyarsk, 660041, Russian Federation)
  • Stolyar S.V. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation, Siberian Federal University, Svobodniy 79, Krasnoyarsk, 660041, Russian Federation, Krasnoyarsk Scientific Center, Federal Research Center KSC SB RAS, Akademgorodok 50, Krasnoyarsk, 660036, Russian Federation)
  • Knyazev Y.V. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)
  • Yaroslavtsev R.N. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation, Krasnoyarsk Scientific Center, Federal Research Center KSC SB RAS, Akademgorodok 50, Krasnoyarsk, 660036, Russian Federation)
  • Pankrats A.I. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation, Siberian Federal University, Svobodniy 79, Krasnoyarsk, 660041, Russian Federation)
  • Vorotynov A.M. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)
  • Krasikov A.A. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)
  • Velikanov D.A. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)
  • Bayukov O.A. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)
  • Ladygina V.P. (Krasnoyarsk Scientific Center, Federal Research Center KSC SB RAS, Akademgorodok 50, Krasnoyarsk, 660036, Russian Federation)
  • Iskhakov R.S. (Kirensky Institute of Physics, Federal Research Center KSC SB RAS, Akademgorodok 50, bld. 38, Krasnoyarsk, 660036, Russian Federation)