  The acoustic-electric transformation in high-quality FeSe single crystals is
studied. In zero magnetic field we observe an abnormally strong electromagnetic
radiation induced by a transverse elastic wave. Usually a radiation of such
intensity and polarization is observed only in metals subjected to a high
magnetic field (the radiation is caused by the Hall current). We argue that in
FeSe in zero magnetic field it is caused by the piezomagnetic effect which is
most probably of dynamical origin. We find that the piezomagnetism survives
under the transition from the normal to superconducting state. In the
superconducting state the electromagnetic signal decreases with decreasing
temperature that is connected with the change in the London penetration depth.
