Magnetic interactions in the ludwigiteNi2FeO2BO3

Abstract

We present an investigation of the magnetic properties of the ludwigite Ni 2 FeO 2 BO 3 . This material is an oxyborate that presents in its crystalline structure subunits in the form of walls where the transition metal ions are located. Our Mössbauer, ac susceptibility, and magnetization measurements show that Fe and Ni ions form two independent subsystems in this material down to T N ϭ15 K. We explain this behavior in terms of a hierarchy of interactions.

Magnetic structure of Cu2MnBO5 ludwigite: thermodynamic, magnetic properties and neutron diffraction study

“…The magnetic structure of Cu 2 MnBO 5 is more complex than in Fe 3 BO 5 -the directions of all the four magnetic moments do not coincide with the principal crystallographic directions in the crystal, which is most likely caused by the Jahn−Teller effect. In addition, the small moment of the copper ions in site 1 (2a) indicates the incomplete magnetic ordering on this site, which is confirmed by the magnetic (anomaly in the magnetization curves) and thermodynamic properties and is characteristic of heterometallic ludwigites [2,4,7,28]. The strong dependence of the magnetization on the applied magnetic field in the region of the second anomaly in the temperature dependences of magnetization needs further investigations of the magnetic and thermodynamic properties in weak magnetic fields.…”

Uniaxial magnetic anisotropy in Co2.25Fe0.75OBartolomé1, Arauzo2, Kazak3 et al. 2011Phys. Rev. B

“…The heterometallic compounds, where M and M are ions of different sorts, have been so far the object of different studies. [1][2][3][4] The ions in the 4-2-4 positions form so-called triads arranged as the rungs of a three-leg ladder of type I, which constitutes the main element of the ludwigite crystal structure. The distance between the transition ions in the sites 2 and 4 is the shortest and allows direct overlap of their electron orbitals.…”

“…(2) At T N1 = 112 K, there is an antiferromagnetic transition (AFM1) where the Fe 2 and Fe 4 moments become ordered, and they share one electron in a mixed-valence state. Otherwise, Fe 1 and Fe 3 sublattices are disordered, although Fe 3 is subject to a transferred weak hyperfine field from the already ordered Fe 2 and Fe 4 sublattices. (3) On further cooling, a new transition at T N2 = 74 K is observed where Fe 1 and Fe 3 also become ordered, and all other Fe moments reorient giving rise to a canted weak ferromagnetic (F) phase.…”

Magnetism and structure of Ni2MnBO5 ludwigite

“…(Me1, Me2 -transition metals) with a ludwigite structure are the members of a large class of compounds have very interesting features, such as charge ordering, existence of several magnetic subsystems ordered at different temperatures and in perpendicular directions, reversal magnetization, spin-glass state [1][2][3][4][5]. Due to these extraordinary properties oxyborates with a ludwigite structure are promising materials for possible applications.…”

“…Due to these extraordinary properties oxyborates with a ludwigite structure are promising materials for possible applications. Moreover, these compounds are good model objects due to the complex quasi-two-dimensional structure including low-dimensional elements -linear chains, zig-zag walls and three-leg ladders [1][2][3] and large number of magnetic ions with different valence states, including the heterovalent cations of one transition metal, per unit cell. The ludwigites structure may contain not only trivalent and bivalent cations of transition metals but it can contain tetravalent cations substituting 2M 3+ =M 2+ +M 4+ .…”