  Repeated uniform switching of the magnetization of thin films of
ferrimagnetic amorphous Gd$_{x}$(FeCo)$_{1-x}$ in response to single fast laser
pulses is well established. Here we report unusual toggle switching in thin
films of sperimagnetic amorphous Dy$_x$Co$_{1-x}$ and Tb$_x$Co$_{1-x}$ with
$\it{x} \simeq$ 0.25 irradiated with single 200 fs pulses of 800 nm laser
light. The samples have strong local random anisotropy due to the non-S state
rare earth. The compensation temperature of the films is $\le$ 180 K and their
Curie temperature is $\simeq$ 500 K. They are mostly switched by the first
pulse, and subsequent pulses lead to partial re-switching of a decreasing
amount of the irradiated area, with a granular structure of submicron regions
of switched and unswitched material. Individual switched domains about 700 nm
in size are observed around the edge of the irradiated spots where the fluence
is at the threshold for switching. Results are discussed in terms of a random
anisotropy model where the ratio of local anisotropy to exchange is temperature
dependent and close to the threshold for strong pinning.
