Antiferromagnetism of Zn_0.87Mn_0.13Fe₂O₄

Abstract

Abstract The magnetic structure of Zn 0.87 Mn 0.13 Fe 2 O 4 polycrystalline samples has been studied by neutron diffraction at 4.2 °K. The indices of the magnetic peaks observed are hkl /2 with l and h + k odd only, where hkl are the indices for the spinel‐type unit cell. The absence of magnetic contributions in the reflections with even l indicates the antiferromagnetic type of ordering. The appearance of a liquid‐type diffuse peak under the strong magnetic reflections (10 1/2) suggests that the long‐range magnetic order both in the A and B sites is still not complete at 4.2 °K. In the proposed model the long‐range magnetic ordering in the A sublattice has been neglected. The magnetic ordering inthe B sites can be described in terms of four sublattices, 1, 2, 3, 4, each containing the positions: x , y , z ; XY , z ; Y , x , 1/2 — z ; y , X , 1/2 — z ; +(0, 0, 0); (1/2, 1/2, 1/2) where x , y , z are: 1/8, 1/8, 5/16; 1/8, 1/8, 13/16; 1/8, 5/8, 9/16; 1/8, 5/8, 1/16. The sublattice 1, 2 (and 3, 4) have opposite spin alignment. The angle between 1, 3 (and 2, 4) lattices could not be determined from the powder neutron data. The value of the magnetic moment for Fe 3+ was determined to be (3.0 ± 0.1) μ B . The magnetic transition temperature was found to occur at (11.0 ± 0.5) °K.