  All liquids (except helium due to quantum effects) crystallize at low
temperatures, forming ordered structures. The competition between disorder,
which stabilizes the liquid phase, and energy, which favors the ordered
crystalline structure, inevitably turns in favor of the latter when temperature
is lowered and the entropic contribution to the free energy becomes
progressively less and less relevant. The "liquid" state survives at low
temperatures only as a glass, an out-of-equilibrium arrested state of matter.
This textbook description holds inevitably for atomic and molecular systems,
where the interaction between particles is set by quantum mechanical laws. The
question remains whether the same physics hold for colloidal particles, where
inter-particle interactions are usually short-ranged and tunable. Here we show
that for patchy colloids with limited valence, conditions can be found for
which the disordered liquid phase is stable all the way down to the
zero-temperature limit. Our results offer interesting cues for understanding
the stability of gels and the glass forming ability of atomic and molecular
network glasses.
