Spin waves in paramagnetic BCC iron: spin dynamics simulations
  Large scale computer simulations are used to elucidate a longstanding controversy regarding the existence, or otherwise, of spin waves in paramagnetic BCC iron. Spin dynamics simulations of the dynamic structure factor of a Heisenberg model of Fe with first principles interactions reveal that well defined peaks persist far above Curie temperature T_c. At large wave vectors these peaks can be ascribed to propagating spin waves, at small wave vectors the peaks correspond to over-damped spin waves. Paradoxically, spin wave excitations exist despite only limited magnetic short-range order at and above T_c. 
Xiuping Tao (1), D. P. Landau (1), T. C. Schulthess (2), G. M. Stocks   (3) ((1) Center for Simulational Physics, Univ. of G...