Equivalent circuit of a thin film recording head

It is assumed that fast and slow relaxation processes both occur in a thin film recording head. Linear response theory is applied to derive an equivalent circuit, which consists of a resistor, describing the coil resistance, in series with an inductor, describing the fast relaxation process, in series with a parallel inductor - resistor combination whose time constant is that of the slow relaxation process. The complex impedance of a head was measured over a frequency range of 10 kHz to 12 MHz. An excellent fit to the experimental data was obtained by adjusting the values of the equivalent circuit elements.