Dynamic hysteresis in microscopic systems with static and fluctuating barriers: the pattern of zero and non-zero temperature responses

The zero temperature quantum dynamics of a periodically driven particle mov ing in a bi-stable potential with a static barrier height is shown to susta in hysteresis loops. If the barrier height fluctuates randomly the loop are a shrinks and passes through a minimum at a critical frequency of fluctuati on (Omega (0)(C)). At non-zero temperatures, the loop area passes through a maximum at a critical fluctuation frequency (Omega (T)(C)). The overall ba rrier crossing rates (by tunneling and overbarrier processes) display exact ly similar responses. The loop area (A) over tilde reveals a clear maximum as a function of driving frequency (omega (d)) at zero temperature while fo r T > 0, two maxima occur on the (A) over tilde-omega plot. The actual cros sing rates also display similar resonance like responses to the driving fie ld. (C) 2001 Elsevier Science B.V. All fights reserved.