Threshold switching delayed response in Ferrite memory cores

Slow switching in the threshold region of Mg
0.5
Mn
0.4
Zn
0.5
Fe
1. 6
O
4
toroids has been studied to elucidate physical processes with inherently different time constants, confluent in faster switching. Threshold switching from the reset state occurs by a large Barkhausen jump which is considerably delayed from the start of the step field. The delay varies randomly above a minimum value, sometimes exceeding 100 ms. The statistical distribution of this delay has been measured as a function of field and temperature. Interrupted pulse experiments demonstrate that both the delay mechanism and the Barkhausen switching are essentially viscous with a setup time of several μs. The phenomenon is understood in terms of very slow growth of reverse domains by thermal activation, culminating in "avalanche" switchiag of interacting domains.