  Voltage-induced magnetization dynamics in a conically magnetized free layer
with an elliptic cylinder shape is theoretically studied on the basis of the
macrospin model. It is found that an application of voltage pulse can induce
the precessional switching of magnetization even at zero-bias magnetic field,
which is of substantial importance for device applications such as
voltage-controlled nonvolatile memory. Analytical expressions of the conditions
for precessional switching are derived.
