Seagate Technology Incorporated

Hans J&uuml;rgen Richter

Erol Girt

Li-Ping Wang

Jason L Pressesky

Samuel Dacke Harkness

Stabilized recording media including coupled discontinuous and continuous magnetic layers

A method for non-destructive measurement of dynamic coercivity is disclosed. In this method, magnetic media is DC erased by applying a forward DC magnetic field to the magnetic media such that the magnetic moments in the magnetic media are substantially aligned. A specified number of reversed magnetic field pulses are then applied to the magnetic media in a direction opposite to the forward DC magnetic field, wherein the intensity of the reversed magnetic field pulses is less than the remanent coercivity of the magnetic media. The broadband medium noise of the magnetic media is measured. The intensity of the reversed magnetic field pulses is then repeatedly and incrementally increased and applied to the write head for the specified number of pulses, the intensity of the reversed magnetic field pulses eventually exceeding the remanent coercivity of the magnetic media. For each intensity level of the reversed magnetic field pulses, the broadband medium noise is again measured. The coercivity of the magnetic media is derived from the reversed magnetic field pulse intensity at which the broadband medium noise is a maximum. The entire process may be repeated for different numbers of pulses in order to measure dynamic coercivity.

System and method for non-destructive measurement of dynamic coercivity effects

An apparatus and a method for measuring the magnetic properties of recording media. Particularly, the invention is directed to the measurement of the coercivity of recording media having high coercivity values. The apparatus for measuring the magnetic properties of recording media contains a thermal source to increase the temperature of a selected portion of the recording media, thus temporally decreasing the coercivity of the recording media in the selected portion. Magnetic transitions are induced by applying a magnetic field to the regions of the medium affected by the thermal source. The electromagnet applies an incrementally increasing DC field to the selected portion to generate variable magnetization data.

Apparatus and method for measuring magnetic properties of recording mediums

A method for measuring the total track width of a test track and adjacent erase bands written over an erased area of magnetic media is disclosed. The test track has a known test track center and effective track width, and contains a periodic signal having a known maximum signal strength. An erase is performed at a certain position from the test track center, followed by a reading of the remaining signal strength of the test track, measured at the test track center. The remaining signal strength is stored as a data value as a function of the position of the erase. The erase, reading, and data value storage steps are repeated at various positions from the test track center, each position being successively closer to the test track center. When the remaining signal strength is less than 50% of the maximum signal strength, the test track is rewritten. The erase, reading, and data value storage steps are repeated at various positions from the test track center, this time on the opposite side of the test track. When the remaining signal strength is less than 50% of the maximum signal strength, the erase process may be terminated. From the stored data values, two additional data values are derived which represent the test track right and left boundary locations. The distance between the test track right and left boundary locations represents the total track width.

Growing community of inventors

Palo Alto, CA, United States of America

Hans Jürgen Richter

Growing community of inventors

Palo Alto, CA, United States of America

Hans J&uuml;rgen Richter

Hans Jürgen Richter