Thermally assisted magnetic recording on a bit-patterned medium by using a near-field optical head with a beaked metallic plate

A near-field optical head with a beaked metallic plate was used for writing marks on a Co∕Pd bit-patterned medium with a diameter of 20–25nm and a pitch of 30nm. Magnetic-force-microscope images of the medium show that the magnetizations of single bits were selectively reversed by the head. The light-utilization efficiency (defined as the ratio of the absorbed power in the medium to the incident light power) was estimated from the writing condition used and thermal modeling as about 5%.