  We report device level damping measurements using spin-torque driven
ferromagnetic resonance on perpendicular magnetic random-access memory (MRAM)
cells. It is shown that thermal agitation enhances the apparent damping for
cells smaller than about 55 nm. The effect is fundamental and does not reflect
a true damping increase. In addition to the thermal effect, it is still found
that device level damping is higher than film level damping and increases with
decreasing cell size. This is attributed to edge damage caused by device
patterning.
