Perpendicular recording technology has recently been introduced
in hard disk drives for computer and consumer electronics
applications. Although conceptualized in the late 1970s, making
a product with perpendicular recording that has competing
performance, reliability, and price advantage over the prevalent
longitudinal recording technology has taken about three decades.
One reason for the late entry of perpendicular recording is that
the longitudinal recording technology was quite successful in
overcoming many of its problems and in staying competitive.
Other reasons are the risks, problems, and investment needed in
making a successful transition to perpendicular recording
technology. Iwasaki and co-workers came up with many inventions
in the late 1970s, such as single-pole head, CoCr alloy media
with a perpendicular anisotropy, and recording media with soft
magnetic underlayers [S. Iwasaki and K. Takemura, IEEE Trans.
Magn. 11, 1173 (1975); S. Iwasaki and Y. Nakamura, ibid. 14, 436
(1978); S. Iwasaki, Y. Na