Strong magnetic short-range order has been observed in Fe and Ni above the Curie temperature Tc. The origin of this short-range order has always been somewhat of an enigma. The authors give here a simple theory to show that the ferromagnetic coupling J1 between nearest neighbours is weaker in the ferromagnetic state than in the completely disordered local moment state. Thus it is relatively easy for the system to disorder on a coarse length scale, retaining locally a substantial degree of ferromagnetic order.
 

Europhysics Letters, 12 545-50, 1990.