PROPAGATING ENERGY MODES IN THE CLASSICAL HEISENBERG CHAIN - MAGNONS AND 2ND MAGNONS

The ferromagnetically coupled classical Heisenberg chain in an applied magnetic field has been studied by computer simulation. The results indicate the presence of a second collective mode, in addition to the damped spin-wave-like modes which have previously been observed in the absence of a magnetic field. For intermediate wavelengths, the mode manifests itself by well-defined oscillations in the energy-density correlation function, and by a second peak in the spectrum of the longitudinal spin-density correlation functions. © 1979 The American Physical Society.