Giant Magnetoelectric Effect in HoAl_3(BO_3)_4
  A giant magnetoelectric polarization is found in HoAl$_3$(BO$_3$)$_4$. The polarization in transverse field geometry at 70 kOe reaches 3600 $\mu C/m^2$ which is significantly higher than reported values of linear magnetoelectric or even multiferroic compounds. The magnetostrictive effect is also measured and compared with the magnetoelectricity. The results show that spin-lattice coupling in HoAl$_3$(BO$_3$)$_4$ is extremely strong and that the magnetic field causes a large polar distortion of the ionic positions in the unit cell. 
K.-C. Liang, R. P. Chaudhury, B. Lorenz, Y. Y. Sun, L. N.   Bezmaternykh, V. L. Temerov, and C. W. Chu
cond-mat.str-el cond-mat.mtrl-sci