Magnetic domain detector

Abstract

Single wall domains are moved synchronously in a sheet of magnetic material along channels defined by magnetically soft overlays as an in-plane magnetic field reorients. A detector is described which includes as an integral part thereof a portion of the overlay defining the propagation channels.

What is claimed is: 
     
       1. Apparatus comprising magnetic material in a plane in which single wall domains can be moved and having a first surface, a magnetically soft overlay adjacent said first surface, said overlay comprising spaced elements having geometries to move single wall domains from input to output positions in response to a reorienting in-plane field, a plurality of electrical conductors connected to one of said elements at said output position, means for providing an electric current connected to said conductors and means for detecting the effect of a domain on said current. 
     
     
       2. Apparatus in accordance with claim 1 wherein said overlay comprises bar and T-shaped elements and said in-plane field reorients by rotation. 
     
     
       3. Apparatus in accordance with claim 2 wherein said means for providing an electric current is connected to a first pair of said plurality of electrical conductors affixed to one of said T-shaped elements, the conductors of said first pair being spaced-apart from one another along the direction of movement of a domain. 
     
     
       4. Apparatus in accordance with claim 3 wherein said means for detecting comprises a second pair of said plurality of electrical conductors affixed to said one of said T-shaped elements, said conductors of said second pair being spaced-apart from one another along a direction perpendicular to the direction of movement of a domain. 
     
     
       5. Apparatus in accordance with claim 4 including two of said T-shaped elements each having first and second pairs of electrical conductors, like designated pairs of each being connected electrically in series. 
     
     
       6. Apparatus in accordance with claim 4 wherein said overlay has a geometry to move single wall domains along a plurality of channels from input to associated output positions, one of each of said first and second electrical conductor pairs being affixed to an I-shaped element at each of said output positions. .Iadd. 7. A magnetic bubble domain system in which said bubble domains can be non-destructively sensed, comprising: a magnetic medium capable of supporting single wall magnetic bubble domains;   sensing means located adjacent said medium for detecting said bubble domains when the magnetic flux of said domains intercepts said sensing means, said magnetic flux being sufficient to change the electrical properties of said sensing means, wherein said sensing means comprises a sensing element whose properties depend upon the magnetic flux thereacross,   means for establishing current flow through said sensing element, and   means to detect said change of said properties of said sensing element.   
     
     
        .Iaddend..Iadd. 8.  A magnetic bubble domain system in which magnetic bubble domains are sensed, comprising: a magnetic sheet in which said bubble domains exist,   a sensing element located in flux-coupling proximity to the stray magnetic field from said bubble domains, the properties of said sensing element changing when said element is intercepted by the stray magnetic field of said bubble domains,   electrical means for providing current through said sensing element,   detection means responsive to a change in said properties of said sensing element for detection of said bubble domains. .Iaddend..Iadd. 9. The system of claim 8, where said sensing element is comprised of magnetically soft material. .Iaddend..Iadd. 10. The system of claim 8, further including propagation means for moving said bubble domains into flux-coupling proximity to said sensing element. .Iaddend. .Iadd. 11. The system of claim 10, where said sensing element is a portion of said propagation means. .Iaddend..Iadd. 12. The system of claim 10, where said sensing element and said propagation means are comprised of the same material. .Iaddend..Iadd. 13. The system of claim 12, where said propagation means and said sensing elements are comprised of magnetically soft material. .Iaddend..Iadd. 14. A magnetic bubble domain system comprising:   a magnetic sheet in which said bubble domains exist,   at least one sensing device located in flux-coupling proximity to the stray magnetic field associated with said bubble domains, said sensing device providing an output indicative of a change in electrical properties of said sensing device when a magnetic field intercepting it changes, said sensing device comprising:   a sensing element whose properties change when the stray magnetic field of a bubble domain intercepts it,   an electrical means for providing current through said element,   a detection means responsive to said change of properties for providing an output indicative of the presence and absence of said bubble domains in flux-coupling proximity to said sensing element,   propagation means for moving said bubble domains into positions of flux-coupling proximity to said magneto-resistive sensing element.   
     
     
        .Iaddend..Iadd. 15.  The system of claim 14, where said sensing element is a portion of said propagation means. .Iaddend..Iadd. 16. The system of claim 14, where said sensing element and said propagation means are comprised of magnetically soft material. .Iaddend.