Influence of the degree of inversion on magnetic properties of MnFe<inf>2</inf>O<inf>4</inf>

Abstract

The cation distribution of single crystal manganese ferrites Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-y</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> [Mn <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2-y</inf> ]O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.06 \leq y \leq 0.24</tex> was modified by appropriate heat treatment at temperatures 300-600°C. With these samples the Curie temperature, the magnetocrystalline anisotropy, the spontaneous magnetization and the differential susceptibility at high magnetic fields were studied. The experiments enabled us to determine the magnitude of the molecular field coefficient N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Mn(A)-Fe(B)</inf> = 89 and to estimate the main part of the contribution to the magnetocrystalline anisotropy in MnFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> which was found to come from Fe <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> in octahedral sites. High field susceptibility measurements confirmed the applicability of the noncolinear arrangement of magnetic moments in MnFe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</inf> which supposes that Mn(B) spins make an angle of 53° with the direction of the total magnetization.