Quadratic Magnetoelectric Effect and Magnetic Field Induced Pyroelectric   Effect in Multiferroic BaMnF4
  The experimental studies of magnetoelectric effects in pulse magnetic field up to 250 kOe and their theoretical analysis on the basis of magnetic symmetry consideration are carried out. It is shown that the nonvanishing components of quadratic magnetoelectric effect tensor corresponding to the electric polarization along b- and c-axes point out the triclinic distortion of the crystal symmetry. Anomalous temperature dependence of magnetically induced polarization Pa(Hb) testifies to the magnetically induced pyroelectric effect. The torque curves measurements show the deflection of the spin orientation from the b-axis at 9 degrees of arc. 
A.K. Zvezdin, G.P. Vorob'ev, A.M. Kadomtseva, Yu.F. Popov, D.V. Belov,   A.P. Pyatakov