  I suggest and examine artificial material which has exponentially degenerate
vacuum state. The corresponding Hamiltonian contains only exotic four-spin
interaction term. Each vacuum state is realized as a particular spin
configuration separated from others by potential barriers. The benefit of such
system in practical applications is that it can be used as high density
magnetic recording system which can reduce storage of one bit information to
$nm$ scale. The information is stored as a particular vacuum state of the
system. The process of recording can be visualized as a process in which the
system moves from one vacuum state to another. Storing information in the form
of different vacuum states separated by potential barriers will allow to
protect it from fluctuations and for a longer time. These materials can be
realized as lattices of nuclear spins with specially adjusted interactions. The
planes of flipped spins can in principle be of atomic scale.
