| US 7,601,443 B2 | ||
| Perpendicular magnetic recording media with laminated soft magnetic underlayer | ||
| Chee-kheng Lim, Suwon-si (Korea, Republic of); Yong-su Kim, Seoul (Korea, Republic of); Byung-kyu Lee, Seoul (Korea, Republic of); Hoon-sang Oh, Seongnam-si (Korea, Republic of); and Tae-hyo Lee, Cheonan-si (Korea, Republic of) | ||
| Assigned to Samsung Electronics Co., Ltd., Suwon-si (Korea, Republic of) | ||
| Filed on Oct. 27, 2005, as Appl. No. 11/259,085. | ||
| Claims priority of application No. 10-2004-0086537 (KR), filed on Oct. 28, 2004. | ||
| Prior Publication US 2006/0093865 A1, May 04, 2006 | ||
| Int. Cl. G11B 5/66 (2006.01); G11B 5/667 (2006.01); G11B 5/673 (2006.01) | ||
| U.S. Cl. 428—828.1 [428/829] | 18 Claims |
| 1. A perpendicular magnetic recording medium comprising:
a substrate;
a perpendicular magnetic recording layer disposed on the substrate; and
a soft magnetic underlayer (SUL) interposed between the substrate and the perpendicular magnetic recording layer, the soft
magnetic underlayer comprising,
a first magnetic layer and a second magnetic layer having unidirectional magnetic anisotropies in directions opposite to each
other by an exchange bias;
an antiferromagnetic layer interposed between the first magnetic layer and the second magnetic layer;
a non-magnetic layer disposed at least on one of the first magnetic layer and the second magnetic layer; and
a third magnetic layer disposed on the non-magnetic layer and antiferromagnetically bonded to the at least one of the first
and second magnetic layers which has the non-magnetic layer disposed thereon, to have a uniaxial magnetic anisotropy,
wherein the first magnetic layer is farther from the substrate than the second magnetic layer, and
wherein the second magnetic layer has a saturation magnetization greater than a saturation magnetization of the first magnetic
layer.
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