Power spectrum scaling in anomalous kinetic roughening of surfaces

19 pages, 6 figures.-- PACS nrs.: 05.40.+j; 05.70.Ln; 68.35.Fx.In this paper we study kinetically rough surfaces which display anomalous scaling in their local properties such as roughness, or height-height correlation function. By studying the power spectrum of the surface and its relation to the height-height correlation, we distinguish two independent causes for anomalous scaling. One is super-roughening (global roughness exponent larger than or equal to one), even if the spectrum behaves nonanamalously. Another cause is what we term an intrinsically anomalous spectrum, in whose scaling an independent exponent exists, which induces different scaling properties for small and large length scales (that is, the surface is not self-affine). In this case, the surface does not need to be super-rough in order to display anomalous scaling. In both cases, we show how to extract the independent exponents and scaling relations from the correlation functions, and we illustrate our analysis with two exactly solvable examples. One is the simplest linear equation for molecular beam epitaxy, well known to display anomalous scaling due to super-roughening, The second example is a random diffusion equation, which features anomalous scaling independent of the value of the global roughness exponent below or above one.J.M.L. acknowledges the Postdoctoral Program of Universidad de Cantabria for support at Instituto de Física de cantabria where most of this work has been made. This work has been supported by DGICyT of the Spanish Government under Project Nr. PB93-0054-C02-02.Publicad