  A new mechanism of low frequency (1/f-like) noise generation is described and
analyzed. It is attributed to higher frequency asymmetric resonance modes,
which are stimulated by a random factor, e.g. due to thermal excitation.
One-dimensional models of bi-harmonic and non-linear asymmetric oscillators are
presented to prove the concept, and a method of detecting the effect is
developed. The method is then applied to experimental data, in order to show
that the effect exists in magnetoresistive readers.
