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 including a first data storage layer defining a first plane, 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 wherein the second data storage layer is formed from a multi-layer structure exhibiting an antiparallel coupling state at the ambient temperatures;
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 plane and the second plane, and wherein the third data storage layer is formed from a multi-layer structure exhibiting an antiparallel coupling state at the ambient temperatures;
a control system adapted to heat the first data storage layer to transition the first data storage layer from the antiparallel coupling state to a receiving state where coercivity of the first data storage layer drops below a write threshold; and
a plurality of write elements proximate to the first data storage layer, wherein the write elements are adapted to apply magnetic fields to the first data storage layer to create a plurality of magnetic domains in the first data storage layer representing a plurality of bits;
wherein the control system is further adapted to cool the first data storage layer to transition the first data storage layer from the receiving state to the antiparallel coupling state to store the magnetic domains in the first data storage layer.
2. The magnetic memory of claim 1 wherein:
the control system is further adapted to heat the second data storage layer to transition the second data storage layer from the antiparallel coupling state to a receiving state where coercivity of the second data storage layer drops below a write threshold;
the control system is further adapted to heat the first data storage layer to transition the first data storage layer from the antiparallel coupling state to a parallel coupling state where the magnetic domains representing stored data are emitted as external stray fields that imprint magnetic domains in the second data storage layer;
the control system is further adapted to cool the second data storage layer to transition the second data storage layer from the receiving state to the antiparallel coupling state; and
the control system is further adapted to cool the first data storage layer to transition the first data storage layer from the parallel coupling state to the antiparallel coupling state.
3. The magnetic memory of claim 2 wherein:
the control system is further adapted to heat the third data storage layer to transition the third data storage layer from the antiparallel coupling state to a receiving state where coercivity of the third data storage layer drops below a write threshold;
the control system is further adapted to heat the second data storage layer to transition the second data storage layer from the antiparallel coupling to a parallel coupling state where the magnetic domains representing stored data are emitted as external stray fields that imprint magnetic domains in the third data storage layer;
the control system is further adapted to cool the third data storage layer to transition the third data storage layer from the receiving state to the antiparallel coupling state; and
the control system is further adapted to cool the second data storage layer to transition the second data storage layer from the parallel coupling state to the antiparallel coupling state.
4. The magnetic memory of claim 1 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 a Curie temperature of the second ferromagnetic layer.
5. The magnetic memory of claim 4 wherein:
the control system is adapted to heat the second ferromagnetic layer of the first data storage layer above its Curie temperature with the first ferromagnetic layer and the third ferromagnetic layer below their Curie temperatures to transition the first data storage layer from the antiparallel coupling state to a parallel coupling state.