Spatially inhomogeneous ultrafast precessional magnetization reversal

Spatially resolved measurements of quasiballistic precessional magnetic switching in a microstructure are presented. A technique is introduced to suppress remanent end domains and allow a completely uniform, almost-perfect-macrospin initial state. Though the precessional response to a transverse magnetic field pulse is initially spatially uniform, and macrospin characteristics can be emulated, dephasing still occurs leading to nonuniformity and transient demagnetization. These nonuniformities are intensified when using coincident longitudinal and transverse pulses created by crossing current wires. The results have implications for the reliability of ballistic precessional switching in magnetic devices.