Structural and spectroscopic properties of the polar antiferromagnet Ni2MnTeO6

Abstract

We present a structural and spectroscopic study of a new compound Ni 2 MnTeO 6 , closely related to the polar antiferromagnet Ni 3 TeO 6 known to show a colossal magnetoelectric effect and pronounced elementary magnetoelectric excitations. For the first time, we prepared single crystals and polycrystalline samples of Ni 2 MnTeO 6 showing the same polar structure as Ni 3 TeO 6 from room temperature down to 4 K with the R3 space group symmetry. Magnetic and dielectric measurements have indicated an antiferromagnetic phase transition at T N ≈70 K, almost 20 K higher than that of Ni 3 TeO 6. Extensive infrared, Raman and THz spectroscopy experiments were employed for investigating lattice and spin excitations, revealing all phonons predicted by the factor group analysis. THz spectra below T N reveal one new excitation, which is strongly influenced by external magnetic field, thus assigned to a magnon.

Evolving spin periodicity and lock-in transition in the frustrated ordered ilmenite-type β−Mn2InSbO6

“…[5] However, despite the possible combinations, only 15 polar A 2 BB'O 6 double corundum-related compounds have been reported to date. Of these, three are theoretical predictions [ 6 , 7 ] , four synthesised at ambient pressures [8,9,10] and the rest can only be stabilised under high pressure and temperature conditions [11,12,13,14,15,16,17,18,19] (Supplementary Table S2).…”

Structural, magnetic, and spin dynamical properties of the polar antiferromagnets Ni3−xCoxTeOSkiadopoulou1, Retuerto2, Borodavka3 et al. 2020Phys. Rev. BSelf Cite10020View full textAdd to dashboardCite

“…The marked discontinuities that occur at ∼4 T in the frequencies of at least four of the excitations, are probably linked to the spin-flop transition, observed also by the magnetization measurements [Fig. 2 [7,8,10], as well as the spin-orbit coupling contribution from Co 3+ (3d [6]).…”

“…The magnetic structures of both compounds, determined by NPD, correspond to an incommensurate AFM helical with the magnetic moments lying in the ab plane, in clear contrast with the collinear out-of-plane spin structure of Ni 3 TeO 6 and Ni 2 MnTeO 6 [1,3,6]. The magnetic propagation vectors are k 1 = (0, 0, 1.299( 4)) and k 2 = (0, 0, 1.2109(1)), for Ni 2 CoTeO 6 and NiCo 2 TeO 6 at 3 and 1.5 K, respectively.…”

“…Since Ni 3 TeO 6 presents a collinear AFM spin structure, the spinlattice coupling mechanism (symmetric exchange striction) is most probably responsible for the emergent dynamical ME effect. A similar polar antiferromagnet Ni 2 MnTeO 6 , undergoes an AFM phase transition at T N ≈ 70 K, almost 20 K higher than Ni 3 TeO 6 , while keeping the same polar rhombohedral R3 space group symmetry [6]. A dielectric anomaly at T N suggests a ME behavior, and a magnetic field-sensitive spin excitation appears below T N in the THz range.…”

“…At least five spin excitations appear below T N for both compounds, and the one at ∼15 cm −1 is simultaneously seen in the Raman spectra. The arrows in parts (a), (b), (e), and (f) indicate the temperature decrease from 300 to 5 K, whereas in (c), (d), (g), and (h), they show the increase of the external magnetic field from 0 to 7 T. magnetism of Co 3 TeO 6[7,8,10], as well as the spin-orbit coupling contribution from Co 3+ (3d[6]). The 15-cm −1 mode seen in Raman spectra [Fig.5(e)], possibly corresponds to the one in the THz spectra at ∼17 cm −1 (0 T), and it shows a strong magnetic field dependence.…”