REVERSIBLE TRANSVERSE SUSCEPTIBILITY OF PARTICULATE RECORDING MEDIA

The response of a system to an infinitesimal perturbation becomes singular if the system changes its degree of metastability, i.e., if it has an inflection point. This theory is used to calculate the reversible transverse susceptibility chi(t) of a single domain particle executing a major hysteresis loop under the influence of a field H(t) applied at an angle beta to the easy axis. Thermal relaxation is taken into account and the response of the nonequilibrium system to the infinitesimal field h(t) = h sin omegat, h perpendicular-to H, is found. The resultant chi(t) is studied as a function of beta, temperature, and of the frequency OMEGA of the biasing field H.