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JETP Letters

, Volume 105, Issue 11, pp 700–705 | Cite as

Novel insight into the effect of disappearance of the Morin transition in hematite nanoparticles

  • M. A. Chuev
  • I. N. Mishchenko
  • S. P. Kubrin
  • T. A. Lastovina
Condensed Matter

Abstract

An alternative treatment of the well-known effect of a decrease in the Morin transition temperature in hematite with a decrease in the size of crystallites to the complete disappearance of the transition for nanoparticles smaller than 20 nm is proposed. In contrast to the standard speculative explanation of this effect in terms of the effect of surface and defectiveness of grains, we suggest that the decisive factor is an increase in the contribution of the shape anisotropy of particles with a decrease in their size, which is responsible for the spread of orientations of the axes of the resulting magnetic anisotropy with respect to the crystallographic axes. Our reasons are confirmed by a numerical analysis of Mössbauer spectra of hematite nanoparticles within the continuous model of magnetic dynamics of an ensemble of antiferromagnetic nanoparticles in the two-sublattice approximation generalized to the existence of weak ferromagnetism (Dzyaloshinskii interaction).

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Copyright information

© Pleiades Publishing, Inc. 2017

Authors and Affiliations

  • M. A. Chuev
    • 1
    • 2
  • I. N. Mishchenko
    • 1
    • 2
  • S. P. Kubrin
    • 3
  • T. A. Lastovina
    • 4
  1. 1.Institute of Physics and TechnologyRussian Academy of SciencesMoscowRussia
  2. 2.National Research Center Kurchatov InstituteMoscowRussia
  3. 3.Research Institute of PhysicsSouthern Federal UniversityRostov-on-DonRussia
  4. 4.International Research Center Intellectual MaterialsSouthern Federal UniversityRostov-on-DonRussia

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