Magnetic storage and reproducing system with a low permeability keeper and a self-biased magnetoresistive reproduce head

A magnetic recording medium for use in a recording/reproducing system of the type in which a bias flux is applied to the recording medium to define a signal transfer zone, comprising:

• a non-magnetic substrate;
• a magnetically coercive layer whose magnetization is controlled to store magnetic signals;
• and
• a layer of magnetic material having a low permeability when unsaturated and a thickness such that a portion of said layer of low permeability material becomes saturated by an applied bias flux whose magnitude is less than that required to alter the magnetization of said coercive layer, wherein the applied bias flux establishes the signal transfer zone.

A magnetic recording medium for use in a recording/reproducing system in which magnetic information is transferred between a transducer and the record medium, comprising:

• a non-magnetic substrate;
• a layer of magnetically coercive material in which the magnetic information is stored;
• and
• a magnetic material having a low permeability when unsaturated and disposed on the substrate in a manner such that said low permeability material becomes selectively saturated during the transfer of information between the transducer and said layer of magnetically coercive material, whereby flux from one recorded transition is coupled to the head during a read operation.

A magnetic recording medium comprising:

• a non-magnetic substrate;
• a first layer of magnetic material for storing magnetically defined information therein;
• and
• a second layer of magnetic material having a low permeability when unsaturated and a thickness relative to said first layer such that the magnitude of magnetic flux required to saturate said second layer is less than the magnitude required to alter information stored in said first layer, wherein said second layer can be selectively saturated to form an aperture therein during transfer of information from said first layer that increases the gradient of transferred flux.