  We show that a surface acoustic wave (SAW) applied across the terminals of a
magnetic tunnel junction (MTJ) decreases both the (time-averaged) parallel and
antiparallel resistances of the MTJ, with the latter decreasing much more than
the former. This results in a decrease of the tunneling magnetoresistance (TMR)
ratio. The coercivities of the free and fixed layer of the MTJ, however, are
not affected significantly, suggesting that the SAW does not cause large-angle
magnetization rotation in the magnetic layers through the inverse
magnetostriction (Villari) effect at the power levels used. This study sheds
light on the dynamical behavior of an MTJ under periodic compressive and
tensile strain.
