Electric Field Control of the Magnetic Chiralities in Ferroaxial MultiferroicRbFe(MoO4)2

Abstract

The coupling of magnetic chiralities to the ferroelectric polarization in multiferroic RbFe(MoO4)2 is investigated by neutron spherical polarimetry. Because of the axiality of the crystal structure below T(c)=190 K, helicity and triangular chirality are symmetric-exchange coupled, explaining the onset of the ferroelectricity in this proper-screw magnetic structure--a mechanism that can be generalized to other systems with ferroaxial distortions in the crystal structure. With an applied electric field, we demonstrate control of the chiralities in both structural domains simultaneously.

First-principles study of multiferroicRbFe(MoO4)2

“…This insensitivity of polarization to out-of-plane helicity is also proposed by Kenzelmann et al 16 Therefore, according to our calculation, the polarization in RFMO is entirely determined by the triangular chirality of the ion spins in the plane, i.e., P c = c 1 σ t . This is consistent with our previous spherical neutron polarimetry experiments 15 , where the chiral domain population could be reversed by an applied electric field, so that flipping P always resulted in a simultaneous flip of σ t . Even though the magnetoelectric coupling c 2 Aσ h is allowed by symmetry, our results indicate that this term is very small in RFMO.…”

“…In a previous experimental paper, 15 some authors of this paper proposed that the helical magnetic structure structure in RFMO, the origin of which remained unclear, is in fact induced by the structural axiality through symmetric exchange. We also show that the axial distorarXiv:1403.1413v1 [cond-mat.mtrl-sci] 6 Mar 2014 tion can give rise to a second component of the electrical polarization, so that the total polarization can be written phenomenologically as P c = c 1 σ t + c 2 Aσ h , where c 1 and c 2 are constants, σ t represents the in plane triangular chirality, σ h is the magnetic helicity along the c direction, and A is the component of the axial rotation parallel to the electric polarization (in RFMO, the ferroaxial vector is A = (0, 0, A), hence A is the magnitude of the ferroaxial distortion whose sign is determined by the structural rotation direction).…”

“…10 These theories explain very well the experimental observations in, for example, the canonical multiferroics TbMn 2 O 5 , TbMnO 3 and many other compounds. 6,11,12 Recently, a new class of magnetoferroelectric materials has been discovered in which the electric polarization is perpendicular to the spin rotation plane, [13][14][15] and cannot be explained by the aforementioned mechanisms. In particular, the KNB theory predicts that the polarization should lie in the plane of rotation of the spins.…”

“…RbFe(MoO 4 ) 2 , referred to as RFMO hereafter, is an obvious candidate to investigate this phenomenon, since it is ferroaxial at low temperatures (point group 3) and has a particularly simple atomic structure and magnetic exchange path ways. 15 The RFMO crystal structure consists of an alternate stacking of a magnetic Fe 3+ layer, two MoO 4 layers (Mo 6+ in the centre of O 4 tetrahedra) and one Rb 1+ layer, as shown in Fig. 1(a).…”

Helical multiferroics for electric field controlled quantum information processing

“…Electric field control of the magnetic chirality in the ferroaxial MF system RbFe(MoO 4 ) 2 was addressed in Ref. [63]. (b) Electric field fidelity susceptibility.…”