Roughness of time series in a critical interface model.

We study roughness probability distribution functions (PDFs) of the time signal for a critical interface model, which is known to provide a good description of Barkhausen noise in soft ferromagnets. Starting with time "windows" of data collection much larger than the system's internal "loading time" (related to demagnetization effects), we show that the initial Gaussian shape of the PDF evolves into a double-peaked structure as window width decreases. We advance a plausible physical explanation for such a structure, which is broadly compatible with the observed numerical data. Connections to experiment are suggested.