Unraveling the nature of ferrimagnetism and associated exchange interactions in distorted honeycomb Ni4Nb2O9

Magnetization reversal study of Ni 4−x Zn x Nb2O9 compounds using Monte Carlo simulations

“…Despite the differences in α, in both cases, MF and MC, β > α and g b < g a as expected for the N-type ferrimagnet, according to Néel classification. Similar results were obtained by Thota et al [14] in the MF approach using asymptotic expressions for high temperatures.…”

“…The jump of the magnetization of the FCW curve at the switching temperature is greater in MC than in MF, and the switching temperature is smaller. Experimental results on Ni 4 Nb 2 O 9 reported by Thota et al [14] and Meng et al [13] show similar behavior, where FCW curves switch at a given temperature.…”

“…In this compound, ferrimagnetism arises due to the balance of two ferromagnetic lattices, corresponding to the two different Ni sites (A and BB), which are antiparallel to each other. The MR is due to the different temperature dependence of the magnetization of the A-layer and BB-layers [13,14]. This system was first studied by Ehrenberg et al [4] using MF calculations, finding a very good description of the MR.…”

“…These experiments are discussed and compared with those of magnetoelectric P 3c1M 4 A 2 O 9 compounds, whose structure derives from corundum. Thota et al [14] present a theoretical analysis deriving a single set of antiferromagnetic exchange constants between the Ni 2+ ions on the A-and BB-layers. Using this set, the authors could explain the temperature dependence of magnetization above and below the Néel temperature.…”

The Ni4−xCoxNb2O9 phase diagram: from magnetization reversal to linear magnetoelectricity

“…The impact of the Co substitution on the magnetic anisotropy is also very important in the FIM zone without MR, with remnant magnetizations and coercive fields varying depending on x and temperature. These FIM compounds are thus an interesting area for theoreticians, to model and predict the magnetic behaviors vs. x , T and H , such as the interesting results recently published by S. Thota et al 39 who determined the antiferromagnetic exchanges constants J AB / k B = 6.98 K > J AA / k B = 4.27 K > J B′B′ / k B = 1.40 K in Ni 4 Nb 2 O 9 . The nature of the substituting elements has also to be taken into account since the impact of the electronic configurations is obvious, at least because direct interaction via t 2g orbitals is possible for Co 2+ but not possible for Ni 2+ , due to the full occupancy of the t 2g levels, and even worse in the case of non-magnetic elements, like Mg 2+ or Zn 2+ .…”