Abstract: The active component of an electronic article surveillance amorphous marker has retained mechanical stress, which may be provided in the course of manufacture thereof, and may be relieved for deactivating the marker. One method for providing such active component is to obtain amorphous metal wire directly from the rapid quench of molten metal. A second method, usable for both wire and ribbon markers, involves annealing the wire or ribbon in twisted state and using same constrained in untwisted state. The marker is deactivated by relieving the stress retained and various practices are shown in this respect.

Abstract: An electronic surveillance system marker comprises an active component responsive to incident magnetic energy for causing an associated article surveillance system to render an output alarm and deactivatable, through change in the molecular organization of the active component, without requirement for disruption of the unitary character of the component or change in its chemical composition. The marker component is selected to be of molecularly unorganized, e.g., amorphous, matter and the deactivation step involves molecularly organizing such matter, e.g., by rendering crystalline at least a portion of the component. The amorphous matter is preferably selected to be a metal composition. The deactivation step is desirably practiced by maintaining such portion of the marker component at a temperature above the crystallization temperature of the component and thereby to crystallize a coercive force in the portion different from the coercive force in the remainder of the component.

Abstract: A marker for an electronic article surveillance system is disclosed comprising a body of magnetic material with retained stress and having a magnetic hysteresis loop with a large Barkhausen discontinuity such that, upon exposure of the marker to an external magnetic field whose field strength in the direction opposing the instantaneous magnetic polarization of the marker exceeds a predetermined threshold value, there results a regenerative reversal of the magnetic polarization of the marker. An electronic article surveillance system and a method utilizing the marker are also disclosed. Exciting the marker with a low frequency and low field strength, so long as the field strength exceeds the low threshold level for the marker, causes a regenerative reversal of magnetic polarity generating a harmonically rich pulse that is readily detected and easily distinguished.