  Electrical control of photogenerated THz spin current pulses from a
spintronic emitter has been at the forefront for the development of scalable,
cost-efficient, wideband opto-spintronics devices. Artificially combined
ferroelectric and ferromagnet heterostructure provides the potential avenue to
control the spin dynamics efficiently utilizing the magnetoelectric coupling.
The demonstration of the electric field control of spin dynamics has so far
been limited up to gigahertz frequencies. Here, we demonstrate the electric
field mediated piezoelectric strain control of photogenerated THz spin current
pulse from a multiferroic spintronic emitter. The phase reversal of the THz
spin current pulse is obtained from the combined effect of piezoelectric strain
and a small constant magnetic field applied opposite to the initial
magnetization of the ferromagnet. The piezoelectric strain-controlled phase
switching of THz spin current thus opens a door to develop efficient strain
engineered scalable on-chip THz spintronics devices.
