YCrWO₆: Polar and Magnetic Oxide with CaTa₂O₆-Related Structure

Abstract

A new polar and magnetic oxide, YCrWO 6 , was successfully synthesized and characterized. YCrWO 6 crystallizes in polar orthorhombic space group Pna2 1 (no. 33) of edgesharing dimers of CrO 6 and WO 6 octahedra, which are connected by corner-sharing to form a three-dimensional framework structure with Y 3+ cations located in the channels. The structure of YCrWO 6 is related to that of CaTa 2 O 6 ; however, the ordering of Cr 3+ and W 6+ in the octahedral sites breaks the inversion symmetry of the parent CaTa 2 O 6 structure. X-ray absorption near edge spectroscopy of YCrWO 6 confirmed the oxidation state of Cr 3+ and W 6+ . Temperature-dependent optical second harmonic generation measurements on YCrWO 6 confirmed the noncentrosymmetric character and evidenced a noncentrosymmetric-tocentrosymmetric phase transition above 800 °C. Piezoresponse force microscopy measurements on YCrWO 6 at room temperature show strong piezoelectric domains. Magnetic measurements of YCrWO 6 indicate antiferromagnetic order at T N of ∼22 K with Weiss temperature of −34.66 K.

Magnetocapacitance effect and magnetoelectric coupling in type-II multiferroic HoFeWO6

“…By comparing these results and the electronic configuration of elemental Ho, Fe, and W and using Hund's law, one would estimate the oxidation states as 3+, 3+, and 6+, respectively. This is quite consistent with our XAS and XMCD results and also in good agreement with previous reports [28,30]. The density of states calculations also confirm that orthorhombic HoFeWO 6 is an insulator with a wide band gap of 3.7 eV, as shown in Fig.…”

“…In aeschynite-type materials with the general formula of RMM O 6 (R=rare-earth; M, M =transition metals), due to symmetry constraints, the crystal structure will adopt a polar space group, Pna2 1 (No. 33), if M and M are ordered [30]. 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].…”

Crystal and magnetic structure of polar oxide HoCrWO6

“…HoCrWO 6 has three-dimensional crystal structure consisting of edge sharing pair of WO 6 and CrO 6 octahedra similar to DyCrWO 6 and YCrWO 6 , as shown in Figure 1b. This result is consistent with the previously reported polar crystal structure of YCrWO 6 (25) because Y 3+ and Ho 3+ have almost the same values of ionic radii. The structure of HoCrWO 6 can be taken to be derived from the euxenite (Pbcn) type Ho(TaTi)O 6 or aeschynite (Pnma) type Dy(TaTi)O 6 (28).…”

“…Therefore, this material family might provide new insight into how the magnetoelectric coupling is affected by the presence of noncentrosymmetricity in the paramagnetic state. Previous studies (24)(25)(26) were performed on YCrWO 6 , YFeWO 6 , DyCrWO 6 , DyFeWO 6 , EuFeWO 6 , TbFeWO 6 . Even though both RCrWO 6 and RFeWO 6 (R = Dy, Y) compounds have the same polar crystal structure, ferroelectric polarization was only observed in the magnetic state of RFeWO 6 (24)(25)(26) through magnetoelectric coupling.…”

“…Previous studies (24)(25)(26) were performed on YCrWO 6 , YFeWO 6 , DyCrWO 6 , DyFeWO 6 , EuFeWO 6 , TbFeWO 6 . Even though both RCrWO 6 and RFeWO 6 (R = Dy, Y) compounds have the same polar crystal structure, ferroelectric polarization was only observed in the magnetic state of RFeWO 6 (24)(25)(26) through magnetoelectric coupling. The absence of electric polarization in Cr-based compounds was explained based on the quasi collinear arrangement of Cr moments (26) and possible absence of magnetoelectric coupling.…”