Title :
Hc measurement of microscopic regions on thin film magnetic disc using longitudinal Kerr effect
Author :
Abe, K. ; Fujimaki, S. ; Furusawa, K. ; Kataoka, H. ; Takagaki, T.
Author_Institution :
Hitachi Ltd., Yokohama, Japan
fDate :
9/1/1989 12:00:00 AM
Abstract :
A longitudinal Kerr magnetooptical microscope system with a read/write testing unit and a positioning unit was developed for nondestructive measurement of the coercive force (Hc) in thin-film magnetic disks. This system measures the magnetooptical hysteresis loop from an area 2-30 μm in diameter on a disk with a C/CoNi/Cr layer. The magnetic field strength at the disk surface was estimated from the coil current in a Weiss-type magnet. The absolute value of the field strength was calibrated by a Hall sensor. The actual Hc values were measured and compared with the result obtained by a vibrating sample magnetometer in order to determine the accuracy, which was found to be within 2%. It took 36 min. to complete the H c measurement at 144 points over a 5.25 in. disk for a mean spot size of 30 μm
Keywords :
Kerr magneto-optical effect; coercive force; hard discs; magnetic variables measurement; quality control; 30 micron; 36 min; 5.25 in; C-CoNi-Cr layer; Hc measurement; Hall sensor; Weiss-type magnet; coercive force measurement; hard disks; longitudinal Kerr effect; longitudinal Kerr magnetooptical microscope system; longitudinal recording discs; magnetic field strength; magnetooptical hysteresis loop; microscopic regions; nondestructive measurement; positioning unit; read/write testing unit; rigid discs; spot size; thin film magnetic disc; thin-film magnetic disks; vibrating sample magnetometer; Area measurement; Coercive force; Force measurement; Magnetic field measurement; Magnetic films; Magnetic force microscopy; Magnetic hysteresis; Nondestructive testing; Position measurement; System testing;
Journal_Title :
Magnetics, IEEE Transactions on
