Incommensurate magnetic structure ofYMn2O5: A stringent test of the multiferroic mechanism

Abstract

We have determined the magnetic structure of the low-temperature incommensurate phase of multiferroic YMn 2 O 5 using single-crystal neutron diffraction. By employing corepresentation analysis, we have ensured full compliance with both symmetry and physical constraints, so that the electrical polarization must lie along the b axis, as observed. The evolution of the spin components and propagation through the commensurateincommensurate phase boundary identifies the exchange-striction mechanism as the primary driving force for ferroelectricity.

Resonant soft X-ray scattering studies of multiferroic YMn2O5

“…The peak positions at the Mn L 2,3 -and O K edges coincide for all temperatures and are in good agreement with the reported positions by neutron scattering [14][15][16]18]. Thanks to the high resolution and the high count rate of the peak, there was no problem in distinguishing the coexisting C-and LTIC-peaks around T 3 (Fig.…”

“…At T 2 = 39 K the AFM order becomes commensurate (C) with q C = (1/2, 0, 1/4) [14][15][16] and a finite P appears [17]. Upon further cooling, low-temperature incommensurate (LTIC) AFM order sets in at T 3 = 19 K with q LTIC = (0.48, 0, 0.29) [14,18]. This transition is connected to a sign change and a reduction in magnitude of P [17].…”

Ferrielectricity in DyMn2O5: A golden touchstone for multiferroicity of RMn2O5 family

“…[51][52][53][54][55][56][57][58][59][60][61][62][63][64] Phenomenological theories on electric polarization has been developed, whose predictions seem to be qualitatively consistent with experimental results. 65À67 If only the Mn 3þ and Mn 4þ spins are considered, the polarization is believed to be generated via the second mechanism shown in Fig.…”

“…Based on this mechanism, a consensus on the ferroelectricity has been reached regarding the following several issues, while some issues remain unclear. [51][52][53][54][55][56][57][58][59][60][61][62][63][64] (1) No matter magnetic or nonmagnetic R, all the multiferroic RMn 2 O 5 members have their polarization along the b-axis without exception. A connection of this property with the spin structures allows an argument that the polarization is essentially generated by the collinear Mn moments while the noncollinear moments play only minor roles if any.…”

Advances in the understanding of multiferroics through soft X-ray diffraction

“…X-ray diffraction has proved an important tool in investigating the complex magnetic structures of multiferroic materials. Although neutron diffraction is still the most powerful technique for determining an overall magnetic structure [11][12][13][14][15], X-ray diffraction provides the ability to probe not only individual elemental contributions, but furthermore the hybridisation between different bands. Such hybridisation has been shown to polarise the Tb 5d states by the manganese 4p states in TbMnO 3 [16], and a similar signal from hybridisation was also observed in RMn 2 O 5 compounds [17][18][19].…”