  Magnetic switch with perpendicular magnetic anisotropy (PMA) is a promising
method for controlling magnetization in several applications like magnetic
tunnel junction and magnetic memory. However, incoherence happens during the
switch process and lower the switch frequency of the magnetic bits. Symmetry
broking can help solve this problem. Here, we present a field-free method for
the symmetry broking and then increase the switch speed of the magnetization. A
strain-mediated method with geometric asymmetry is presented here. In this
work, we build a finite element model that consists a 50 nanometer diameter
nanodisk with a varied thickness on the top of a 50 nanometer thick PZT
(Pby[ZrxTi1-x]O3) thin film. The results show a 66% faster switch than symmetry
PMA switching (0.85 nanosecond to 0.29 nanosecond) under same energy
consumption. Finally, we explore the mechanism of the symmetry broking of
varying thickness nanodot with calculating the energy profile.
