Static deformation of a ferromagnet in alternating magnetic field

•Static deformation of a ferromagnet in ac magnetic field was observed.•Deformation arises due to even dependence of magnetostriction vs. magnetic field.•Value of the strain is proportional to the second derivative of magnetostriction.•AC field induced strain can reach ~50% of the saturation magnetostriction.

Static deformation of a ferromagnet under an action of ac magnetic field was observed and investigated in this work. The effect is due to even and nonlinear dependence of magnetostriction on magnetic field. It is shown that the deformation is proportional to the second derivative of magnetostriction over the field at low fields and depends on the static bias field. The deformation grows nearly linearly and then saturates with increasing ac field. For the samples with very different parameters like permendur and nickel the ac field induced static strain can reach ~50% of the saturation magnetostriction.