0000000000282283
AUTHOR
Laurent Bellaiche
Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3
We have observed the magnetoelectric (ME) response at room temperature and above in high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) and PFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of the paramagnetoelectric (PME) coefficient shows a pronounced maximum near the ferroelectric-to-paraelectric phase transition temperature, T C, and then decreases sharply to zero for T > T C. The maximal PME coefficient in PFN is about 4 × 10−18 s/A. The theoretical description of the PME effect, within the framework of a Landau theory of phase transitions allowing for realistic temperature dependences of spontaneous polarization, dielectric and magnetic susceptibilities, …
Revisiting spin cycloids in multiferroic BiFeO3
We revisit the inverse spin current model that has been previously used to explain the existence of magnetic cycloids in bulk multiferroic ${\mathrm{BiFeO}}_{3}$. Using a first-principles-based effective Hamiltonian method, and in combination with Monte Carlo simulations, we predict a magnetic phase diagram as a function of first- and second-nearest-neighbor interaction strength in the spin current model and show that, in contrast with previous understanding, both first and second nearest neighbors have to be taken into account to be in accordance with experimental findings, including the existence of type-1 and type-2 cycloids with, respectively, $[1\overline{1}0]$ and $[11\overline{2}]$ p…
Magnetic Interactions in BiFeO$_3$: a First-Principles Study
First-principles calculations, in combination with the four-state energy mapping method, are performed to extract the magnetic interaction parameters of multiferroic ${\mathrm{BiFeO}}_{3}$. Such parameters include the symmetric exchange (SE) couplings and the Dzyaloshinskii-Moriya (DM) interactions up to second-nearest neighbors, as well as the single-ion anisotropy (SIA). All magnetic parameters are obtained not only for the $R3c$ structural ground state, but also for the $R3m$ and $R\overline{3}c$ phases in order to determine the effects of ferroelectricity and antiferrodistortion distortions, respectively, on these magnetic parameters. In particular, two different second-nearest-neighbor…