Strong short-range magnetic order in a frustrated fcc lattice and its possible role in the iron structural transformation

The magnetic properties of a frustrated Heisenberg antiferromagnet with the fcc lattice and exchange interaction between the nearest (J(1)) and next-to-nearest (J(2)) neighbors are studied in this work. For the collinear phase with the wave vector Q = (pi,pi,pi), the equations of the self-consistent spin-wave theory are obtained and solved numerically for the sublattice magnetization and the averaged short-range order parameter. The dependence of the Neel temperature T(N) on the ratio J(2)/J(1) is found. It is shown that, in the case of a sufficiently strong frustration, strong short-range magnetic order persists over a wide temperature range above T(N). The possible application of this result to the mechanism of structural phase transition from alpha-Fe to gamma-Fe is considered.