Pierluigi Contucci, Peter Kleban, Andreas Knauf.
A Fully Magnetizing Phase Transition.
(566K, Postscript)

ABSTRACT.  We analyze the Farey spin chain, a one dimensional spin system with 
effective interaction decaying like the squared inverse distance. 
Using a polymer model technique, we show that when the temperature 
is decreased below the (single) critical temperature T_c=1/2, the 
magnetization jumps from zero to one.