Tight-binding linear muffin tin orbitals calculations with generalized grad
ient approximation were carried out for the magnetic configurations at the
surface of the ferromagnetic ordered B2 FeCr alloys. For both (001) and (11
1) crystallographic phases, non ferromagnetic configurations are shown to b
e more stable than the ferromagnetic configuration of the bulk alloy. For (
001) surface we display a c(2 x 2) ground state for either Cr or Fe at the
surface. For Cr top layer the magnetic moments are 700% larger than in the
bulk B2 FeCr while they are slightly enhanced for Fe top layer. For (111) s
urface an antiferromagnetic coupling between surface and subsurface is alwa
ys obtained i.e. for either Fe or Cr at the surface. This change of couplin
g between Fe and Cr (from ferromagnetic to antiferromagnetic) is expected t
o be fundamental to any explanation of the experimental results obtained fo
r the interface alloying at the Fe/Cr interfaces.