Static and dynamic aspects of the demagnetizing factor in magnetic thin films with random rough surfaces

We investigate static and dynamic aspects of the demagnetizing factor N in magnetic thin films with random rough surfaces which are described by the r ms amplitude Delta, the correlation length xi, and the roughness exponent H (0 less than or equal to H less than or equal to 1). The demagnetizing fac tor decreases as the surface smoothens (increasing H and/or decreasing rati o Delta/xi), with the exponent H yielding a comparable contribution to N as the roughness ratio Delta/xi. Moreover, for growing films with self-affine surfaces, N decreases with film thickness, closely as a power law for larg e roughness exponents (H similar to 1). Finally, estimates of the demagneti zing factor based on sinusoidal models are shown to be inadequate since the y neglect fine roughness details at short wavelengths (<xi) as depicted by the roughness exponent H. (C) 1999 American Institute of Physics. [S0021-89 79(99)03915-8].