2019/09/12 by Richard Jones, Richard Victor Jones, Rachel Nickel +5
Chemistry · Energy · Materials Science · Mathematics · Physics and Astronomy · #Anisotropy #Atomic physics #Chemistry #Condensed matter physics #Crystal structure #Crystallography #Ferromagnetism #Field (mathematics) #Hyperfine structure #Iron oxide chemistry and applications #Magnetic Properties and Synthesis of Ferrites #Magnetism #Materials science #Mathematics #Monoclinic crystal system #Multiferroics and related materials #Octahedron #Physics #Quantum mechanics #Spin (aerodynamics) #Superexchange #Thermodynamics #cond-mat.mes-hall #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.100.094425
arxiv created 2019/09/12 · openalex publication_date 2019/09/16 · openalex created_date 2019/09/19 · arxiv updated 2019/10/02 · openalex updated_date 2026/08/05
8-nm \ensuremathε\ensuremath-Fe2O3 nanoparticles exhibit a spin reorientation transition that begins at 150 K which is a hallmark of this unique iron-oxide polymorph. We find that the change from the high- to low-temperature magnetic structures has been suppressed by \ensuremath∼50 K. At the spin reorientation temperature, a change of the field-dependent response of the tetrahedral sites in intermediate field strengths (0.25--1.5 T) indicates that a collective tetrahedral distortion occurs to which the octahedral sites adjust, altering the magnetic anisotropy. An abrupt step in the hyperfine parameters' temperature dependencies, especially at 125 K for the hyperfine field associated with the Fe4 tetrahedral sites, suggests strongly that a change in the superexchange pathways is responsible for the spin reorientation.