Ordered aeschynite-type polar magnets RFeWO6 ( R=Dy , Eu, Tb, and Y): A new family of type-II multiferroics

Abstract

We report the discovery of magnetoelectric multiferroicity in a family of oxides, RFeWO 6 (R = Dy, Eu, Tb and Y) that crystallize in a polar aeschynite-type structure ( Pna2 1 )

Crystal and magnetic structure of polar oxide HoCrWO6

“…In this work, we have performed neutron diffraction measurements at 2 K and 18 K where both Ho and Cr sublattices are ordered, similarly to previous work on DyCrWO 6 and DyFeWO 6 (24,26). In previous work (24,26), it was observed that both rare earth and transition metal sublattices order below T N and the magnetic moment on the rare earth site increases progressively as temperature is lowered. It should be mentioned that powder diffraction gives the average intensity and becomes insensitive to slight change in orientation of the moments.…”

“…Since the magnetic structure of HoCrWO 6 is similar to that of DyCrWO 6, the scenario of strongest Cr 3+ -O-O-Cr 3+ antiferromagnetic super-super exchange interaction and weakest Ho 3+ -O-Ho 3+ interaction might also be valid for HoCrWO 6 as presented for DyCrWO 6 through exchange integral calculation (26,(36)(37)(38)(39)(40)(41)(42). In this work, we have performed neutron diffraction measurements at 2 K and 18 K where both Ho and Cr sublattices are ordered, similarly to previous work on DyCrWO 6 and DyFeWO 6 (24,26). In previous work (24,26), it was observed that both rare earth and transition metal sublattices order below T N and the magnetic moment on the rare earth site increases progressively as temperature is lowered.…”

Magnetocapacitance effect and magnetoelectric coupling in type-II multiferroic HoFeWO6

“…In particular, the experimental data can be closely simulated [Fig. 2(c), red solid curve] by considering a noncollinear AFM model, observed by Ghara et al [28] in DyFeWO 6 using neutron diffraction. In this model there are two Fe sites, Fe1 and Fe2, for which spins are arranged antiferromagnetically on two perpendicular planes, ac and bc, respectively.…”

“…Several compounds with a noncentrosymmetric polar structure have also been reported to be magnetoelectric multiferroics, e.g., M 2 Mo 3 O 8 (M=Fe, Mn) [19][20][21], CaBaCo 4 O 7 [22][23][24], Ni 3 TeO 6 [25][26][27], and recently RFeWO 6 (R=Dy, Eu, Tb, and Y) [28]. All of these compounds have a broken inversion symmetry in their paramagnetic region driven by the chemical ordering of their cations, and they show a change in polarization at the magnetic ordering temperature without any sign of structural phase transition, in which the polarization is coupled to the magnetic field.…”

“…It was previously reported that the oxides of RMWO 6 (R=rareearth element and M=V, Cr, and Fe) have an ordered arrangement of M 3+ and W 6+ and that they show an antiferromagnetic (AFM) ordering at low temperature [31]. In addition, it was recently shown by Ghara et al [28] that the compounds of RFeWO 6 (R=Dy, Eu, Tb, and Y) exhibit magnetoelectric multiferroicity. Their neutron diffraction study on DyFeWO 6 revealed a commensurate noncollinear arrangement of Fe 3+ and Dy 3+ spins with the magnetic space group C a c.…”