  While in accordance with Curie's principle, one would intuitively expect that
symmetry of the cause has to be found in the symmetry of the effect, ultrafast
excitation of matter is able to violate this principle. For instance, it is
believed that heating alone, obviously not having the symmetry of a magnetic
field, cannot result in a deterministic reversal of magnetization. However, if
the heating is induced by a femtosecond laser pulse and thus ultrafast, it does
facilitate toggle switching of magnetization between stable bit-states without
any magnetic field at all. Here we show that the regime of ultrafast toggle
switching can be also realized via a mechanism without relying on any heat. The
obvious mismatch between symmetries of the cause and the response can thus be
seen as a violation of Curie's principle. In particular, ultrafast laser
excitation of iron-garnet with linearly polarized light modifies magnetic
anisotropy and thus causes toggling magnetization between two stable bit
states. In contrast to the laser-heat-induced magnetization reversal, this new
regime of 'cold' toggle switching can be observed in ferrimagnets without the
compensation point and in an exceptionally broad temperature range. The control
of magnetic anisotropy required for the toggle switching is accompanied by
lower dissipations, than in the mechanism of laser-induced-heating, but the
dissipations and the switching-time are shown to be competing parameters.
