(a) Schematic illustration of measurement set-up of the magneto-piezoelectric effect (MPE). A EuMnBi2 sample was fixed on a Cu holder of a liquid-He optistat. The lowest temperature of the MPE measurement is 4.5 K. The optistat has a quartz window and the laser is irradiated from a laser Doppler vibrometer to the sample through the quartz window. An AC electric current is applied to the sample along the  direction and the AC displacement is measured along the  direction. Using the Doppler effect of the laser reflected from the sample, the velocity of sample vibration was extracted. The vibration velocity was transferred to the FFT analyzer and numerically integrated with respect to time to obtain the displacement signal. (b) A photograph of the EuMnBi2 sample. The largest plane corresponds to the (001) plane. (110) planes are prepared to measure AC displacements along the  direction. (c) Sample photographs (top row) and frequency spectra of displacement signals (bottom row) at 4.5 K. The MPE measurement was performed at two positions: position-1 and position-2. The red dots in the photographs correspond to the laser spot of the laser Doppler vibrometer. In response to the AC electric current with 10-kHz frequency and 100-mA (zero-to-peak) amplitude, AC displacement signals appear at the same frequency as the AC electric current. The current-induced signals are highlighted by green arrows in the figures. The displacement signals measured on the Cu sample holder are also shown.