Designed Ferromagnetic, Ferroelectric Bi₂NiMnO₆

Abstract

A newly designed ferromagnetic, ferroelectric compound, Bi(2)NiMnO(6), was prepared by high-pressure synthesis at 6 GPa. The crystal structure, as determined by synchrotron X-ray powder diffraction, is a heavily distorted double perovskite with Ni(2+) and Mn(4+) ions ordered in a rock-salt configuration. The presence of 6s(2) lone pairs of Bi(3+) ions and the covalent Bi-O bonds give ferroelectric properties with T(CE) of 485 K, while -Ni(2+)-O-Mn(4+)-O-Ni(2+)- magnetic paths lead to a ferromagnetism with T(CM) of 140 K. This simple material design to distribute two magnetic elements with and without e(g) electrons on B sites of Bi- and Pb-based perovkites can be applied to other Bi(2)M(2+)M'(4+)O(6) and Pb(2)M(3+)M'(5+)O(6) systems to search for newer ferromagnetic ferroelectrics.

Influence of SrTiO3 Buffer Layer on the Ferroelectric Properties of Bi2NiMnO6 Thin Film

“…Azuma et el. reported that the C2 symmetry of this compound allows a spontaneous polarization along the b axis, and a calculation Downloaded by [East Carolina University] at 19:07 04 January 2013 assuming a pointcharge model with the above structural parameters gave a polarization of 20 µC/cm 2 [11]. But the observed polarization is much smaller than the calculated value, because the observed ferroelectric polarization should be a projection along the out-of plane direction.…”

Dielectric properties of (Bi0.9La0.1)2NiMnOLangenberg1, Fina2, Ventura3 et al. 2012Phys. Rev. B

“…The corresponding permittivity is found to be in the range of that reported for BNMO bulk materials. 3 In the high-frequency range, we can also observe a small but perceptible ε (ν) dependence [ Fig. 2(a)], which is at odds with the response of an ideal dielectric, but it is commonly observed in most dielectrics and attributed to the frequency-dependent ac conductivity σ ac .…”

“…In contrast, in bulk BNMO, dielectric permittivity was found to be roughly constant (ε ≈ 200) for temperatures well below T F E . 3 Here, we report on a quantitative study of the apparent temperature-dependent dielectric relaxation of BLNMO thin films, which we prove is driven by the temperature dependence of the resistivity instead of the dielectric relaxation of electric dipoles. Impedance spectroscopy methods 10,12,20 have been used to disentangle extrinsic contributions to the measured permittivity and to extract the temperature dependence of the intrinsic dielectric and resistive properties of (Bi 0.9 La 0.1 ) 2 NiMnO 6 films.…”

“…2 In the case of Bi 2 NiMnO 6 (BNMO) and La 2 NiMnO 6 (LNMO), both compounds are ferromagnetic below T F M ≈ 140 and 280 K, respectively, 3,4 but only the former is ferroelectric (T F E ≈ 485 K). 3 The magnetoelectric coupling might be favored in the solid solution BNMO-LNMO due to the approach of the two transition temperatures (T F M , T F E ), 5 because La-doping in BNMO diminishes the ferroelectric response while it increases the magnetic Curie temperature. 6 It has been shown that in bulk form, 6 up to 20% of La-doping, the structure of (Bi 1−x La x ) 2 NiMnO 6 remains noncentrosymmetric monoclinic C2, for which ferroelectric order would be permitted.…”

Magnetic structure of an incommensurate phase of La-dopedBiFe0.5Sc0.5O3: Role of antisymmetric exchange interactions

“…Finally, let us point out, for completeness, that the magnetic order parameter transforming as the mS 2 irreducible representation does not form a third power invariant with the mR + 4 ⊗ 2 product. The mS 4 representation does form such invariant and provides coupling, when the spins, in the primary G-type configuration, are along the orthorhombic a o axis. The latter situation is, however, unfavorable for the part of the antisymmetric exchange associated with the octahedral tilting, as discussed in the main text.…”