Laminated structure and spin modulation element
A laminated structure according to an embodiment includes: a ferromagnetic layer; and a multiferroic layer formed on one surface of the ferromagnetic layer, wherein the multiferroic layer includes a first region having a tetragonal crystal located on a surface side on the ferromagnetic layer side and a second region having a rhombohedral crystal located further inside than the first region.
1. A laminated structure, comprising:
a ferromagnetic layer; and
a multiferroic layer formed on one surface of the ferromagnetic layer,
wherein the multiferroic layer includes a first region having a tetragonal crystal located on a surface side on the ferromagnetic layer side and a second region having a rhombohedral crystal located further inside than the first region.
2. The laminated structure according to claim 1 , wherein a thickness of the first region is 1 nm or more.
3. The laminated structure according to claim 1 , wherein one surface of the second region on the ferromagnetic layer side is present within 8 nm from a surface of the multiferroic layer on the ferromagnetic layer side.
4. The laminated structure according to claim 1 , wherein a portion of the first region having a tetragonal crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
5. The laminated structure according to claim 1 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
6. The laminated structure according to claim 1 , wherein a plurality of portions of the first region having a tetragonal crystal structure are present and a plurality of portions of the second region having a rhombohedral crystal structure are present.
7. The laminated structure according to claim 1 , wherein the multiferroic layer includes any selected from the group consisting of BiFeO 3 , BiMnO 3 , GaFeO 3 , AlFeO 3 , (Ga, Al)FeO 3 , YMnO 3 , CuFeO 2 , Cr 2 O 3 , Ni 3 Bi 7 O 13 I, LiMnPO 4 , Y 3 Fe 5 O 12 , TbPO 4 , and LiCoPO 4 .
8. The laminated structure according to claim 1 , wherein the ferromagnetic layer is a half metal.
9. The laminated structure according to claim 1 , wherein the ferromagnetic layer includes a Heusler alloy represented by a composition expression of X 2 YZ, X in the composition expression is a transition metal element or a noble metal element from the Co, Fe, Ni, or Cu group in the periodic table, Y is a transition metal from the Mn, V, Cr, or Ti group or the element types for X, and Z is a typical element from Group III to Group V.
10. A spin modulation element, comprising:
the laminated structure according to claim 1 ; and
a nonmagnetic layer and a second ferromagnetic layer sequentially laminated on the ferromagnetic layer of the laminated structure.
11. The laminated structure according to claim 2 , wherein one surface of the second region on the ferromagnetic layer side is present within 8 nm from a surface of the multiferroic layer on the ferromagnetic layer side.
12. The laminated structure according to claim 2 , wherein a portion of the first region having a tetragonal crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
13. The laminated structure according to claim 3 , wherein a portion of the first region having a tetragonal crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
14. The laminated structure according to claim 11 , wherein a portion of the first region having a tetragonal crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
15. The laminated structure according to claim 2 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
16. The laminated structure according to claim 3 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
17. The laminated structure according to claim 4 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
18. The laminated structure according to claim 11 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
19. The laminated structure according to claim 12 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.
20. The laminated structure according to claim 13 , wherein a portion of the second region having a rhombohedral crystal structure occupies an area of 30% or more of one surface of the multiferroic layer when the multiferroic layer is viewed in a plan view in the lamination direction.