Some Properties of Ferromagnetoelectric Nickel-Iodine Boracite, Ni3B7O13I

Abstract

Ferroelectricity and weak ferromagnetism have been found to set on simultaneously in NiaB 7 0 13 I at about 64°K. This is evidenced by dielectric hysteresis, spontaneous Faraday effect, quadratic magnetoelectric hysteresis, etc. The strong coupling between the mutually perpendicular spontaneous polarization-[001]-and spontaneous magnetization-[110]-is such that, when the former is reversed, the latter turns by 90°.The magnetic point group is most probably m'm2'. Dielectric constant, magnetic, and magnetoelectric susceptibilities and magnetic coercive field are shown as a function of temperature.

Defect Chemistry as a Crystal Structure Design Parameter: Intrinsic Point Defects and Ga Substitution in InMnO3

“…For spin-polarized Perdew-Burke-Ernzerhof functionals (PBE), 36 for example, a non-polar ground state is slightly favored for stoichiometric InMnO 3 , whereas the spin-polarized PBE plus Hubbard U (GGA+U) method yields a ferroelectric ground state, in agreement with the likely experimental situation. For our calculations we used the PBE functional in its form that is modified for solids (PBEsol), 37 as this typically gives excellent agreement with experiment for bond lengths and lattice parameters, and added an effective Hubbard U term, U ef f = U − J = 4 eV, in keeping with previous work on InMnO 3 and other hexagonal manganites. 38 With these settings we found the P 6 3 cm phase to be only 4 meV per formula unit lower in energy than the P3c, consistent with the previously calculated near degeneracy of the two phases.…”

“…The search for multiferroic materials, with their multiple coexisting ferroic orders, has been a hotbed of research activity in recent decades [1][2][3][4][5] and has led to the identification of new mechanisms for ferroelectricity that are compatible with the coexistence of magnetism. 6 The so-called improper geometric ferroelectricity identified in the rare-earth hexagonal manganites, RMnO 3 (R=Sc, Y, Dy, Ho, Er, Tm, Yb, Lu, In), is of particular interest and has stimulated research in topics as diverse as high-temperature multiferroism, 7 nanodevices 8,9 and testing of early-universe theories.…”

Magnetic Field‐Induced Ferroelectric Switching in Multiferroic Aurivillius Phase Thin Films at Room Temperature

“…ferromagnetic polarization) induces a switching of the other order parameter (in this example ferroelectric polarization). Examples of single-phase magnetoelectrics include: Cr 2 O 3 (<260 K) 29 , CuO (<230 K) 30 , TbMnO 3 (<27 K) 31 , Ni 3 B 7 O 13 I (<64 K) 32 , DyMn 2 O 5 (<43 K) 33 . The synthesis of novel room temperature single-phase magnetoelectric multiferroic materials is particularly appealing, not only because they have two sets of interesting physical properties with 4 polarization states (positive and negative in both electrical and magnetic polarizations), but also because the multiferroic coupling interactions could lead to a range of potential applications.…”

Magnetic ferroelectric materials

“…Such a couphng has for the first time been demonstrated for Ni3B70i3l (Ascher et al 1966), in which an electric field-induced 180'^ reversai of the spontaneous polarization causes a symmetry-conditioned 90° reorientation of the spontaneous magnetization, and a magnetic field-induced 90° reorientation of the spontaneous magnetization causes a 180" reversai of the spontaneous polarization, Such coupling between the spontaneous polarization and the spontaneous magnetization requires ferroelasticity to be aliowed and leads to nonlinear effects with hystérésis cycles and memory behaviour, whereas the linear and bilinear (spécial case: quadratic) magnetoelectric effects are in principle non-lossy, thermodynamically réversible effects, if domain switching and possible relaxation phenomena are disrcgarded.…”

“…The simultaneous occurrence of ferroelectricity and (weak) ferromagnetism was first discovered in nickel iodine boracite Ni3B70i3l (below 61 K.) (Ascher et al 1966). This compound is a member of a large crystal structure family with the gênerai formula M3B7O13X, where M stands for a bivalent cation of Mg, Cr, Mn, Fe, Ce, Ni, Cu, Zn, etc and X for a monovalent anion like OH", F~, Cl", Br~, I~, or NO3".…”