TY - JOUR

T1 - Superparamagnetic blocking of an ensemble of magnetite nanoparticles upon interparticle interactions

AU - Balaev, D. A.

AU - Semenov, S. V.

AU - Dubrovskiy, A. A.

AU - Yakushkin, S. S.

AU - Kirillov, V. L.

AU - Martyanov, O. N.

PY - 2017/10/15

Y1 - 2017/10/15

N2 - We report on the effect of interparticle magnetic interactions in an ensemble of superparamagnetic magnetite particles with an average size of ~8.4 nm dispersed in the diamagnetic matrix on the blocking of this ensemble in external magnetic field. The two limit cases are investigated: the case of strongly interacting particles, when the value of magnetic dipole-dipole interaction between particles is comparable with the energy of other interactions in the ensemble (the interparticle distance is similar to the nanoparticle diameter) and the case of almost noninteracting particles distant from each other by about ten particle diameters. We demonstrate that the experimental dependence of the blocking temperature on external field is described well within the model [1], in which the density of particles in a nonmagnetic medium is taken into account and the correlation value depends on external magnetic field. The model for describing the magnetic properties of a disperse nanoparticle ensemble is proposed, which makes corrections related to the particle size and mean dipole-dipole interaction energy for the anisotropy constant. The surface magnetic anisotropy of Fe3O4 particles and parameters of the interparticle coupling are estimated.

AB - We report on the effect of interparticle magnetic interactions in an ensemble of superparamagnetic magnetite particles with an average size of ~8.4 nm dispersed in the diamagnetic matrix on the blocking of this ensemble in external magnetic field. The two limit cases are investigated: the case of strongly interacting particles, when the value of magnetic dipole-dipole interaction between particles is comparable with the energy of other interactions in the ensemble (the interparticle distance is similar to the nanoparticle diameter) and the case of almost noninteracting particles distant from each other by about ten particle diameters. We demonstrate that the experimental dependence of the blocking temperature on external field is described well within the model [1], in which the density of particles in a nonmagnetic medium is taken into account and the correlation value depends on external magnetic field. The model for describing the magnetic properties of a disperse nanoparticle ensemble is proposed, which makes corrections related to the particle size and mean dipole-dipole interaction energy for the anisotropy constant. The surface magnetic anisotropy of Fe3O4 particles and parameters of the interparticle coupling are estimated.

KW - Blocking temperature

KW - FeO nanoparticles

KW - Size effect

KW - Superparamagnetic nanoparticles

KW - TEMPERATURE

KW - RESONANCE

KW - Fe3O4 nanoparticles

KW - ANISOTROPY

UR - http://www.scopus.com/inward/record.url?scp=85014224373&partnerID=8YFLogxK

U2 - 10.1016/j.jmmm.2016.12.046

DO - 10.1016/j.jmmm.2016.12.046

M3 - Article

AN - SCOPUS:85014224373

VL - 440

SP - 199

EP - 202

JO - Journal of Magnetism and Magnetic Materials

JF - Journal of Magnetism and Magnetic Materials

SN - 0304-8853

ER -