Amorphous antipilferage marker

Abstract

A magnetic theft detection system marker is adapted to generate magnetic fields at frequencies that (1) are harmonically related to an incident magnetic field applied within an interrogation zone and (2) have selected tones that provide the marker with signal identity. The marker is an elongated, ductile strip of amorphous ferromagnetic material having a composition defined by the formula M a N b O c X d Y e Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-7, "d" ranges from about 5-22, "e" ranges from about 0-15 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25.

What is claimed is: 
     
       1. For use in a magnetic theft detection system, a marker adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, and retaining its signal identity after being flexed or bent, said marker comprising an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula M a  N b  O c  X d  Y e  Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-2.5, "d" ranges from about 12-20.3, "e" ranges from about 0-13 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25. 
     
     
       2. A marker as recited in claim 1, said marker having at least one magnetizable portion integral therewith, the magnetizable portion having coercivity higher than that of said amorphous material. 
     
     
       3. A marker as recited in claim 2, wherein said magnetizable portion is adapted to be magnetized to bias said strip and thereby decrease the amplitude of the magnetic fields generated by said marker. 
     
     
       4. A marker as recited in claim 2, wherein said magnetizable portion comprises a crystalline region of said material. 
     
     
       5. A marker as recited in claim 3, wherein said decrease in amplitude of magnetic fields generated by said marker causes said marker to lose its signal identity. 
     
     
       6. In a magnetic theft detection system marker for generating magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, the improvement wherein: a. said marker comprising an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula M a  N b  O c  X d  Y e  Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-2.5, "d" ranges from about 12-20.3, "e" ranges from about 0-13 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25; and   b. said marker retains its signal identity after being flexed or bent.   
     
     
       7. A magnetic detection system responsive to the presence of an article within an interrogation zone, comprising: a. means for defining an interrogation zone;   b. means for generating a magnetic field within said interrogation zone;   c. a marker secured to an article appointed for passage through said interrogation zone, said marker comprising an elongated, ductile strip of amorphous ferromagnetic metal having a composition consisting essentially of the formula M a  N b  O c  X d  Y e  Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-2.5, "d" ranges from about 12-20.3, "e" ranges from about 0-13 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25, said marker being capable of producing magnetic fields at frequencies which are harmonics of the frequency of an incident field;   d. detecting means for detecting magnetic field variations at selected tones of said harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin, said selected tones providing said marker with signal identity and said marker retaining said signal identity after being flexed or bent.   
     
     
       8. For use in a magnetic theft detection system, a marker adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, said marker comprising an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula M a  N b  O c  X d  Y e  Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-2.5, "d" ranges from about 12-20.3, "e" ranges from about 0-13 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25. .Iadd.9. An article of merchandise having an amorphous antipilferage marker secured thereto, said marker comprising that as recited in claim 8. .Iaddend. .Iadd.10. An article of merchandise as recited in claim 9, comprising book, wearing apparel or appliance. 
     
     
        .Iaddend. .Iadd.11.  For use in a magnetic theft detection system, a marker adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, said marker comprising an iron- or cobalt-based amorphous ferromagnetic alloy comprising at least about 35 atom percent of iron, cobalt, or mixture thereof, and said marker having such ductility as to permit flexing or bending without degradation of the signal identity thereof. .Iaddend. .Iadd.12. A marker as recited in claim 11, said marker comprising an at least 50% glassy strip of said iron- or cobalt-based amorphous ferromagnetic alloy. .Iaddend. .Iadd.13. A marker as recited in claim 12, said marker comprising an at least 80% glassy strip of said iron- or cobalt-based amorphous ferromagnetic alloy. .Iaddend. .Iadd.14. A marker as recited in claim 13, said marker comprising an iron- or cobalt-based amorphous ferromagnetic foil adapted to be bent to a round radius, without fracture, as small as ten times the foil thickness 
     
     
        thereof. .Iaddend. .Iadd.15.  A marker as recited in claim 11, said marker retaining at least 90% of its original harmonic amplitude after flexing or bending. .Iaddend. .Iadd.16. A marker as recited in claim 11, said marker comprising an iron- or cobalt-based amorphous ferromagnetic alloy consisting essentially of the formula M a  N b  O c  X d  Y e  Z f , where M is at least one of iron and cobalt, N is nickel, O is at least one of chromium and molybdenum, X is at least one of boron and phosphorous, Y is silicon, Z is carbon, "a"-"f" are in atom percent, "a" ranges from about 35-85, "b" ranges from about 0-45, "c" ranges from about 0-2.5, "d" ranges from about 12-20.3, "e" ranges from about 0-13 and "f" ranges from about 0-2, and the sum of d+e+f ranges from about 15-25. .Iaddend. .Iadd.17. A marker as recited in claim 11, said iron- or cobalt-based amorphous ferromagnetic alloy comprising at least one the elements boron, phosphorous, carbon, silicon, or mixture thereof. .Iaddend. .Iadd.18. A marker as recited in claim 17, said iron- or cobalt-based amorphous ferromagnetic alloy comprising an Fe-Ni-Mo-B, Fe-Ni-P-B, Fe-Ni-B, Fe-B, Fe-Mo-B, Co-Fe-Mo-B-Si, Fe-C-Si-B, Fe-Co-B-Si or 
     
     
        Fe-C-P glassy metal alloy. .Iaddend. .Iadd.19.  A marker as recited in claim 11, said marker comprising at least one crystalline phase and at least one amorphous phase. .Iaddend. .Iadd.20. A marker as recited in claim 11, said marker comprising an amorphous ferromagnetic strip provided with at least one magnetizable element. .Iaddend. .Iadd.21. A marker as recited in claim 20, said marker comprising a plurality of hard magnetic chips. .Iaddend. .Iadd.22. A marker as recited in claim 21, said marker comprising an ordered pattern of said plurality of hard magnetic chips. .Iaddend. .Iadd.23. A marker as recited in claim 22, said marker comprising at least one ordered row of said plurality of hard magnetic chips. .Iaddend. .Iadd.24. A marker as recited in claim 11, said marker comprising a solid solution of said iron- or cobalt-based amorphous 
     
     
        ferromagnetic alloy. .Iaddend. .Iadd.25.  A marker as recited in claims 8 or 11, said marker comprising a ribbon or foil, wire, or sheet. .Iaddend. .Iadd.26. A marker as recited in claim 25, said marker comprising a ribbon or foil. .Iaddend. .Iadd.27. A marker as recited in claim 25, said marker comprising a wire. .Iaddend. .Iadd.28. A marker as recited in claim 25, said marker comprising a sheet. .Iaddend. .Iadd.29. An article of merchandise having an amorphous antipilferage marker secured thereto, said marker comprising that as recited in claim 11. .Iaddend. .Iadd.30. An article of merchandise as recited in claim 29, comprising book, wearing apparel or appliance. .Iaddend.