Ripple Relaxation Times in Thin Magnetic Films

Abstract

Basically two different models have been proposed to characterize the effect of ripple on magnetization reversal. One of them assumes a long ripple relaxation time compared to thin‐film switching times, the other short. To determine which model best describes switching phenomena, a small‐angle fallback experiment has been devised which detects the change of the ripple reaction torque due to ripple rearrangements. From these data, a ripple relaxation time of 1.1±0.2 nsec was found which was relatively independent of angular dispersion. A theoretical calculation was made similar to that by K. J. Harte except loss was included. Using typical thin‐film values, a 1.3 nsec ripple relaxation time was obtained which is in good agreement with experimental data. Therefore, except for the initial high‐speed rotational process, the fast‐relaxation model should best describe noncoherent rotational‐switching behavior.