Three-dimensional magnetic memory with multi-layer data storage layers
View Patent ↗Magnetic memories and methods are disclosed. A magnetic memory as described herein includes a plurality of stacked data storage layers to form a three-dimensional magnetic memory. The data storage layers are each formed from a multi-layer structure. At ambient temperatures, the multi-layer structures exhibit an antiparallel coupling state with a near zero net magnetic moment. At higher transition temperatures, the multi-layer structures transition from the antiparallel coupling state to a parallel coupling state with a net magnetic moment. At yet higher temperatures, the multi-layer structure transitions from the antiparallel coupling state to a receiving state where the coercivity of the multi-layer structures drops below a particular level so that magnetic fields from write elements or neighboring data storage layers may imprint data into the data storage layer.
1. A magnetic memory, comprising:
a first storage stack having a first data storage layer defining a first plane and adapted to store bits of data; and
a plurality of secondary storage stacks fabricated on top of one another on the first storage stack, wherein each of the secondary storage stacks includes a second data storage layer defining a secondary plane that is parallel to the first plane and adapted to store bits of data;
wherein the first data storage layer and the second data storage layers are each formed from a multi-layer structure exhibiting an antiparallel coupling state at ambient temperatures.
2. The magnetic memory of claim 1 wherein the multi-layer structure further exhibits a transition from the antiparallel coupling state to a parallel coupling state at a transition temperature that is higher than the ambient temperatures.
3. The magnetic memory of claim 2 wherein the multi-layer structure further exhibits a transition from the antiparallel coupling state to a receiving state at a receiving temperature that is higher than the ambient temperatures and the transition temperature, wherein the receiving state represents a drop in coercivity of the multi-layer structure below a write threshold.
4. The magnetic memory of claim 1 wherein the multi-layer structure comprises:
a first ferromagnetic layer;
an antiparallel coupling layer formed on the first ferromagnetic layer;
a second ferromagnetic layer formed on the antiparallel coupling layer; and
a third ferromagnetic layer formed on the second ferromagnetic layer;
wherein the first ferromagnetic layer is antiparallel coupled to the second ferromagnetic layer and the third ferromagnetic layer at the ambient temperatures;
wherein the first ferromagnetic layer is parallel coupled to the third ferromagnetic layer at a transition temperature that is higher than the ambient temperatures.
5. The magnetic memory of claim 4 wherein the first ferromagnetic layer and the third ferromagnetic layer have a Curie temperature that is higher than the Curie temperature of the second ferromagnetic layer.
6. The magnetic memory of claim 4 wherein the first ferromagnetic layer and the third ferromagnetic layer each comprise multi-layer structures comprised of alternating layers of Co and Pd or Pt.
7. The magnetic memory of claim 4 wherein:
the second ferromagnetic layer comprises a multi-layer structure comprised of alternating layers of CoNi and Pd or Pt; and
the antiparallel coupling layer is comprised of Ru or Ir.
8. A method of fabricating a magnetic memory, the method comprising:
forming a first storage stack that includes a first data storage layer defining a first plane and adapted to store bits of data; and
forming a plurality of secondary storage stacks on top of one another on the first storage stack, wherein each of the secondary storage stacks includes a second data storage layer defining a secondary plane that is parallel to the first plane and adapted to store bits of data;
wherein the first data storage layer and the second data storage layers are each formed from a multi-layer structure exhibiting an antiparallel coupling state at ambient temperatures.
9. The method of claim 8 wherein the multi-layer structure further exhibits a transition from the antiparallel coupling state to a parallel coupling state at a transition temperature that is higher than the ambient temperatures.
10. The method of claim 9 wherein the multi-layer structure further exhibits a transition from the antiparallel coupling state to a receiving state at a receiving temperature that is higher than the ambient temperatures and the transition temperature, wherein the receiving state represents a drop in coercivity of the multi-layer structure below a write threshold.
11. The method of claim 10 wherein:
forming a first storage stack comprises forming a first heating layer, forming the first data storage layer, and forming a first insulating layer; and
forming a plurality of secondary storage stacks comprises forming a second heating layer, forming the second data storage layer, and forming a second insulating layer.
12. The method of claim 8 wherein forming the multi-layer structure of the first data storage layer or the second data storage layer comprises:
forming a first ferromagnetic layer;
forming an antiparallel coupling layer on the first ferromagnetic layer;
forming a second ferromagnetic layer on the antiparallel coupling layer; and
forming a third ferromagnetic layer on the second ferromagnetic layer;
wherein the first ferromagnetic layer is antiparallel coupled to the second ferromagnetic layer and the third ferromagnetic layer at the ambient temperatures;
wherein the first ferromagnetic layer is parallel coupled to the third ferromagnetic layer at a transition temperature that is higher than the ambient temperatures.
13. The method of claim 12 wherein the first ferromagnetic layer and the third ferromagnetic layer have a Curie temperature that is higher than the second ferromagnetic layer.
14. The method of claim 12 wherein:
forming the first ferromagnetic layer comprises forming alternating layers of Co and Pd or Pt; and
forming the third ferromagnetic layer comprises forming alternating layers of Co and Pd or Pt.
15. The method of claim 14 wherein:
forming the second ferromagnetic layer comprises forming alternating layers of CoNi and Pd or Pt; and
forming the antiparallel coupling layer comprises forming a layer of Ru or Ir.
16. A magnetic memory, comprising:
a first storage stack including a first data storage layer defining a first plane and adapted to store bits of data, wherein the first data storage layer is formed from a multi-layer structure exhibiting an antiparallel coupling state at ambient temperatures;
a second storage stack proximate to the first storage stack, wherein the second storage stack includes a second data storage layer defining a second plane that is parallel to the first plane and is adapted to store bits of data, and wherein the second data storage layer is formed from a multi-layer structure exhibiting an antiparallel coupling state at the ambient temperatures; and
a third storage stack proximate to the second storage stack, wherein the third storage stack includes a third data storage layer defining a third plane that is parallel to the first and second planes and is adapted to store bits of data, and wherein the third data storage layer is formed from a multi-layer structure exhibiting an antiparallel coupling state at the ambient temperatures.
17. The magnetic memory of claim 16 wherein the multi-layer structure of the first data storage layer includes:
a first ferromagnetic layer;
an antiparallel coupling layer formed on the first ferromagnetic layer;
a second ferromagnetic layer formed on the antiparallel coupling layer; and
a third ferromagnetic layer formed on the second ferromagnetic layer;
wherein the first ferromagnetic layer and the third ferromagnetic layer of the multi-layer structure have a Curie temperature that is higher than the Curie temperature of the second ferromagnetic layer.