Enhancement of elastic-light scattering due to the magnetization instability in ultrathin magnetic films

We have observed magnetic-field-dependent enhancements as large as a factor of 20 of the intensity of elastic-light scattering, from ultrathin magnetic films with perpendicular magnetic anisotropy. High-resolution Brillouin spectroscopy shows that this enhancement reaches its maximum at a critical field (H-crit) where the magnetization starts to incline toward out-of-plane due to the perpendicular anisotropy. We attribute this effect to the microscopic instability due to random fluctuations of the magnetization near H-crit. [S0163-1829(99)00930-3].