Weak ferromagnetism and domain effects in multiferroic LiNbO3-type MnTiO3-II

Abstract

Magnetic order consistent with multiferroism has been observed in the acentric LiNbO 3 -type, high pressure form II of MnTiO 3 using neutron diffraction and magnetization measurements. Spin order below the 28 K magnetic transition has propagation vector (0 0 0), and spins lie in the ab plane. Representation symmetry analysis shows that the antiferromagnetic Mn 2+ spin component observed by neutron scattering, of magnitude 3.9(1) μ B at 2 K, coexists with a weak ferromagnetic component of magnitude 0.0014 μ B . This magnetization is perpendicular to the electrical polarization resulting from cation displacements in this acentric structure, permitting coupled switches of the two ferroic orders. The spin order is stable to fields of at least 5 T; however, facile domain reorientation within the ab plane enhances the antiferromagnetic susceptibility and a constant magnetization/field (M/H ) is observed in field strengths greater than ∼1.5 T. Suppression of the {101} neutron intensity with field follows the same Brillouin-dependence as M/H and enables the antiferromagnetic easy axes to be identified as parallel to the ab plane hexagonal axes.

MnTaO2N: Polar LiNbO3‐type Oxynitride with a Helical Spin Order

“…These values are close to those observed in other LN‐type manganese oxides 20c. 22 The TaO 4 N 2 octahedron is distorted as well with three short (1.99 Å) and three long (2.11 Å) Ta‐O(N) bonds, which are comparable with those of perovskite oxynitrides A TaO 2 N ( A =alkali earth) 23…”

“…The magnetic moment at 6 K is 3.63 μ B , which is lower than the expected value of 5.0 μ B for Mn 2+ in a high spin state. We note, however, that this value is similar to that of MnTiO 3 (3.9 μ B )22 and strongly suggests the existence of strong frustration as pointed out from the magnetic susceptibility measurements.…”

“…Remarkably, MnTaO 2 N undergoes magnetic long‐range order at 25 K, a rare example of magnetic order in transition‐metal oxynitrides. Furthermore, we found a nontrivial helical spin order, as opposed to the isostructural and isoelectronic LN‐type MnTiO 3 with a conventional G ‐type structure ( T N =28 K), with a small spin canting caused by Dzyaloshinskii–Moriya (DM) interactions 22…”

Strain-dependence of the structure and ferroic properties of epitaxial Ni1−xTi1−yO3 thin films grown on sapphire substrates

“…Thin film deposition by molecular beam epitaxy or pulsed laser deposition (PLD) is often the method of choice to prepare high-quality epitaxial films because they allow for the stabilization of otherwise metastable structures and tuning material properties by the introduction of lattice strain. Thin film deposition also eliminates the need for specialized high-pressure apparatus needed for growing crystals of the above MTiO 3 compounds in the LNO-type structure [7][8][9][10].…”

Linear magnetoelectricity at room temperature in perovskite superlattices by design

“…For example, it was shown [13] how a polar distortion -in an antiferromagnetic-paraelectric (AFM-PE) material displaying linear magnetoelectricity -would induce weak-ferromagnetism in the LiNbO 3 structure, e.g., FeTiO 3 [14] or MnSnO 3 [15], and subsequently allow for the electric-field switching of the magnetization by 180…”