Digital magnetoresistive sensor with bias

An apparatus for reading magnetic data fields on a magnetic storage medium comprising:

• a conducting spacer;
• a free layer having a magnetic anisotropy that supports a first and a second stable magnetic state;
• a pinned layer having a fixed magnetic orientation perpendicular to the first and second stable states;
• the free layer, the conducting spacer, and the pinned layer arranged in a laminate with the conducting spacer forming the middle layer of the laminate;
• a magnetic field generator to bias the free layer and cause the first stable magnetic state to rotate to a first biased stable magnetic state and the second stable magnetic state to rotate to a second biased stable magnetic state, wherein the free layer switches between the first and second biased stable magnetic states in response to the magnetic data fields on the magnetic storage medium;
• and
• readback circuitry in communication with the magnetoresistive sensor that determines the value of the magnetic data fields based upon the magnetic state of the magnetoresistive sensor.

A data storage system, comprising:

• a magnetic storage medium having data stored thereon in the form of varying magnetic data fields;
• a magnetoresistive sensor maintained proximate to the storage medium during relative motion between the magnetoresistive sensor and the storage medium;
• the magnetoresistive sensor comprising a free layer, the free layer having a magnetic anisotropy that supports first and second stable magnetic states;
• an alternating current source for biasing the free layer and causing the first stable magnetic state to rotate to a first biased stable magnetic state and the second stable magnetic state to rotate to a second biased stable magnetic state, wherein the free layer switches between the first and second biased stable magnetic states in response to the magnetic data fields on the magnetic storage medium;
• and
• readback circuitry in communication with the magnetoresistive sensor that determines the value of the data based upon the magnetic state of the magnetoresistive sensor.

A method of sensing data stored in sectors on a magnetic medium in the form of varying magnetic fields with a magnetoresistive sensor having a free layer, the free layer having a magnetic anisotropy that supports first and second stable magnetic states, the method comprising the steps of:

• magnetically biasing the free layer wherein the first stable magnetic state rotates to a first biased stable magnetic state and the second stable magnetic state rotates to a second biased stable magnetic state;
• positioning the sensor proximate to a sector of the magnetic medium to be sensed;
• removing the magnetic bias wherein the first biased stable magnetic state rotates to the first stable magnetic state and the second biased stable magnetic state rotates to the second stable magnetic state;
• sensing the magnetic state of the free layer while the magnetic bias is removed.

An apparatus for reading magnetic data fields on a magnetic storage medium comprising:

• a free layer having a magnetic anisotropy that supports a first and a second stable magnetic state;
• a magnetic field generator to bias the free layer and cause the first stable magnetic state to rotate to a first biased stable magnetic state and the second stable magnetic state to rotate to a second biased stable magnetic state, wherein the second stable magnetic state is at least one of parallel or anti-parallel to the first stable magnetic state and an angle between the first biased stable magnetic state and the second biased stable magnetic state is less than 180 degrees;
• and wherein the free layer switches between the first and second biased stable magnetic states in response to the magnetic data fields on the magnetic storage medium;
• a conducting spacer;
• and
• a pinned layer having a fixed magnetic orientation perpendicular to the first and second stable states, the free layer, the conducting spacer, and the pinned layer arranged in a laminate with the conducting spacer forming the middle layer of the laminate.