Antiferroelectric lattice distortion induced by ferroquadrupolar order in ${\text{DyVO}}_4$

The effects of quadrupolar order on structural, magnetic, and dielectric properties have been investigated for ${\text{DyVO}}_4$. Our detailed structure analysis demonstrated that the cooperative Jahn-Teller effect associated with $4f$ ferroquadrupolar order causes the displacement of oxygen ions surrounding a Dy ion, which makes the relative position of a V ion off-center in a ${\text{VO}}_4$ tetrahedron. The lattice distortion well explains antiferroelectriclike anomalies at around the quadrupolar ordering temperature. We also report the Jahn-Teller domain control giving rise to a remarkable magnetocapacitance effect by applying a small magnetic field $\left(\sim 0.1\text{T}\right)$.

Figure 1

(Color online) Crystal structure of ${\text{DyVO}}_4$. (a) Unit cell. (b) The projection along the $c$ axis of the quadrupolar-ordered crystal structure below $T_D$. (c) The JT distortion in a unit cell. Dashed lines represent crystal structure in the high-$T$ phase. Ellipses surrounding Dy ions in (b) and (c) indicate the schematic views of pancakelike charge distributions of $4f$ electrons. Thick arrows in (a) and (c) denote the direction of the local electric polarization in the respective ${\text{VO}}_4$ tetrahedra.

Figure 2

(Color online) Temperature variations in (a) order parameter, (b) magnetization, and (c) electric susceptibility along the $c$ axis at several magnetic fields for single crystals of ${\text{DyVO}}_4$. Magnetic fields were applied along ${\left[100\right]}_{tetra}$. Solid curves show the best least-squares fit of CEF theory to the experimental data points.

Figure 3

(Color online) Magnetic field dependence of (a) relative intensity of the (800) peak, (b) magnetization, (c) magnetocapacitance, and (d) electric displacement measured in an applied electric field at 5 K for single crystals of ${\text{DyVO}}_4$. Magnetic fields were applied along ${\left[100\right]}_{tetra}$. Inset of (a): the (800)/(080) Bragg reflection profiles at selected $B$ in the increasing $B$ run. Inset of (c): $T$ profiles of ${\chi }_a$ and ${\chi }_b$ at 0.2 T.