  We calculate the correlation functions of uniform magnetization in thin
ferromagnetic films for small deviations from equilibrium, by using a
functional formalism. To take account of dissipation and fluctuations
consistently, the magnetization is coupled to a bosonic heat bath. The
correlation functions show strong dependence on the nature of the coupling
between the bath and the system. Depending on what coupling we choose, we show
how the recent results $(\text{J. Appl. Phys. 90, 5768 (2001); Phys. Rev. B 65,
172417 (2002)}) $ obtained by macroscopic methods can be related to the
microscopic treatment adopted here.

Materials Science;Statistical Mechanics