Amorphous antipilferage marker

Claim 1

For use in a magnetic theft detection system, a marker (16) adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone (12) and have selected tones that provide said marker (16) with signal identity, said marker comprising an elongated, ductile strip (18) of amorphous ferromagnetic material, characterized in that the amorphous ferromagnetic material has a value of magnetostriction ranging from +2x10 -6 to -2x10 -6 , and a B-H loop as square as possible; that a test strip of the material having length=10 cm, width=0.3 cm, and thickness 35 pm retains at least 70% of its original harmonic amplitude during stress imposed by flexing the strip 1.5 turns; and that the material is a composition consisting essentially of the formula where X is at least one of Cr, Mo and Nb a-f are in atom percent and the following provisos are applicable: (i) when 14≤(e+f)≤17, with 10SeS17 and 0≤f≤7, then (a) if 2≤d≤4, the values for a, b and c are grouped as follows, (b) if 4≤d≤6, the values for a, b and c are qrouped as follows, (c) if 6≤d≤8, the values for a, b and c are grouped as follows, (ii) when 17≤(e+f)≤20, with 12≤e≤20 and O≤f≤8, then (a) if 0≤d≤2, the values for a, b and c are grouped as follows, (b) if 2≤d≤4, the values for a, b and c are grouped as follows, (c) if 4≤d≤6, the values for a, b and c are grouped as follows, (iii) when 20≤(e+f)≤23, with 8≤e≤23 and 0≤f≤15, then (a) if 0sdS2, the values for a, b and c are grouped as follows, (b) if 2≤d≤4, the values for a, b and c are grouped as follows, (iv) when 23≤(e+f)≤26, with 5≤e≤26 and 0≤f≤20, then (a) if 0≤d≤2, the values for a, b and c are grouped as follows, (v) up to 6 atom percent of the Ni and X component present being, optionally, replaced by Mn; and (vi) up to 2 atom percent of the combined B and Si present being, optionally, replaced by at least one of C, Ge and AI.