| US 7,595,966 B2 | ||
| Multi-valued data recording spin injection magnetization reversal element and device using the element | ||
| Hideaki Watanabe, Kawaguchi (Japan); and Akira Saito, Yokosuka (Japan) | ||
| Assigned to Fuji Electric Holdings Co., Ltd., Kawasaki (Japan) | ||
| Filed on Sep. 12, 2006, as Appl. No. 11/530,931. | ||
| Claims priority of application No. 2005-263923 (JP), filed on Sep. 12, 2005. | ||
| Prior Publication US 2008/0062578 A1, Mar. 13, 2008 | ||
| Int. Cl. G11B 5/39 (2006.01) | ||
| U.S. Cl. 360—324.12 [360/324.2] | 14 Claims |
| 1. A spin injection magnetization reversal element comprising:
a ferromagnetic fixed layer in which the direction of magnetization thereof is substantially fixed in one direction;
a plurality of ferromagnetic free layers, with the number of the layers being n from a first ferromagnetic free layer to an
n-th layer, in each of which the direction of magnetization is variable; and
a plurality of nonmagnetic isolation layers with the number of the layers being n,
wherein
the first ferromagnetic free layer is disposed closest to the ferromagnetic fixed layer and the n-th ferromagnetic free layer
is disposed farthest from the ferromagnetic fixed layer with the n ferromagnetic free layers from the first ferromagnetic
free layer to the n-th ferromagnetic free layer being disposed in order,
one of the isolation layers being disposed between the ferromagnetic fixed layer and the first ferromagnetic free layer,
each one of the rest of the isolation layers is disposed between neighboring ferromagnetic free layers,
the direction of magnetization of each of the ferromagnetic free layers is varied by electron spin injection, and
a relation of Icj−1>Icj (where 2≤j≤n) is satisfied in the ferromagnetic layers, where j is a number given as 1≤j≤n and Icj is a magnetization reversal current density in a j-th ferromagnetic free layer.
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