Magnetic memory device and method of magnetic domain wall motion
A magnetic memory device comprises a first electrode, a second electrode, a laminated structure comprising plural first magnetic layers being provided between the first electrode and the second electrode, a second magnetic layer comprising different composition elements from that of the first magnetic layer and being provided between plural first magnetic layers, a piezoelectric body provided on a opposite side to a side where the first electrode is provided in the laminated structure, and a third electrode applying voltage to the piezoelectric body and provided on a different position from a position where the first electrode is provided in the piezoelectric body.
1. A magnetic memory device comprising:
a first electrode;
a second electrode;
a laminated structure comprising plural first magnetic layers being provided between the first electrode and the second electrode, a second magnetic layer comprising different composition elements from those of the first magnetic layer and being provided between plural first magnetic layers;
a piezoelectric body provided to surround the laminated structure in a laminated direction of the laminated structure; and
a third electrode and a fourth electrode applying a voltage to the piezoelectric body.
2. The device of claim 1 , a sign of a magnetostriction constant of the first magnetic layer is different from a sign of a magnetostriction constant of the second magnetic layer, or an absolute value of the magnetostriction constant of the first magnetic layer is smaller than an absolute value of the magnetostriction constant of the second magnetic layer.
3. The device of claim 1 , the laminated structure further comprising a third magnetic layer comprising a different sign of magnetostriction constant from a sign of magnetostriction constant of the second magnetic layer, the second magnetic layer and the third magnetic layer being provided alternately between the plural first magnetic layers.
4. The device of claim 1 , a magnetization direction of the second magnetic layer is changed when voltage is applied between the third electrode and the fourth electrode.
5. The device of claim 1 , the laminated structure further comprising a third magnetic layer comprising a different sign of magnetostriction constant from a sign of magnetostriction constant of the second magnetic layer, the second magnetic layer and the third magnetic layer being provided alternately between the plural first magnetic layers, and a magnetization direction of the second magnetic layer is changed when a first voltage is applied between the third electrode and the fourth electrode, and a magnetization direction of the third magnetic layer is changed when a second voltage whose sign is different from the first voltage is applied between the first electrode and the third electrode.
6. The device of claim 1 , further comprising a writing section making magnetization direction of the first magnetic layer begin changed when current is applied to the first magnetic layer and being provided on the first magnetic layer, and a reading section detecting resistance changes of the first magnetic layer and begin provided on the first magnetic layer.
7. The device of claim 1 , a cross sectional area of the first magnetic layer in a laminated direction of the first magnetic layer and the second magnetic layer is larger than a cross sectional area of the second magnetic layer in the laminated direction.
8. The device of claim 1 , the piezoelectric body comprising potassium sodium tartrate, zinc oxide, aluminum nitride, lead zirconium titanate, zirconium titanate lanthanum lead, crystal, lithium niobate, lithium tantalate, lithium tetraborate, potassium niobate, langasrte crystalline, or potassium sodium tartrate tetrahydrate.
9. The device of claim 1 , the laminated structure being laminated in perpendicular direction to a substrate, the first magnetic layer and the second magnetic layer comprising GdFe, GdCo, GdFeCo, TbFe, TbCo, TbFeCo, GdTbFe, GdTbCo, DyFe, DyCo, or DyFeCo.
10. The device of claim 1 , the laminated structure being laminated in parallel direction to a substrate, the first magnetic layer and the second magnetic layer being comprised of multilayer of (Co/Ni) or comprising GdFe, GdCo, GdFeCo, TbFe, TbCo, TbFeCo, GdTbFe, GdTbCo, DyFe, DyCo, or DyFeCo.
11. A method of magnetic domain wall motion of the device of claim 1 , comprising a first step applying a current between the first electrode and the second electrode for a first time duration, a second step applying a voltage to the piezoelectric body for a second time duration, wherein a completing time of the second step is after a completing time of the first step.