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US 2014/0177327 A1Published application
Voltage-controlled magnetic anisotropy (vcma) switch and magneto-electric memory (meram)
AssigneeThe Regents of the University of California
InventorsPedram Khalili Amiri, Kang L. Wang, Kosmas Galatsis
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Abstract
Voltage controlled magnetic tunnel junctions and memory devices are described which provide efficient high speed switching of non-volatile magnetic devices at high cell densities. Implementations are described which provide a wide range of voltage control alternatives with in-plane and perpendicular magnetization, bidirectionally switched magnetization, and control of domain wall dynamics.
Claims40
A voltage-controlled magnetic anisotropy (VCMA) switch apparatus, comprising:
- at least two ferromagnetic (FM) layers having a FM fixed layer and a FM free layer;
- a dielectric (DE) layer interposed between said FM fixed layer and said FM free layer;
- and
- wherein material, shape and thickness of said FM free layer and said FM fixed layer are selected to have in-plane (IP) and out-of-plane (OOP) anisotropies;
- wherein material, shape and thickness of said FM free layer is selected to have in-plane (IP) and out-of-plane (OOP) anisotropies which are nearly equal;
- and
- wherein OOP anisotropy of said FM free layer is affected by interface properties between said FM layers and said DE layer, and is controlled by voltages applied across said DE layer as an applied voltage, giving rise to a voltage-controlled magnetic anisotropy (VCMA) effect which switches magnetization orientation of said FM free layer in said apparatus.
4 more elements
A voltage-controlled magneto-electric random access memory (MeRAM) apparatus, comprising:
- at least three ferromagnetic (FM) layers having a FM fixed layer, a FM semi-fixed layer, and a FM free layer;
- wherein said FM semi-fixed layer and said FM free layer are disposed on opposite sides of said FM fixed layer;
- and
- a dielectric (DE) layer interposed between said FM free layer and FM fixed layer;
- a spacer layer separating said FM semi-fixed layer from said FM fixed layer;
- wherein material, shape and thickness of said FM free layer, said FM fixed layer, and said FM semi-fixed layer are selected to have in-plane (IP) and out-of-plane (OOP) anisotropies;
- wherein material, shape and thickness of said FM free layer is selected to have in-plane (IP) and out-of-plane (OOP) anisotropies which are nearly equal;
- wherein material, shape and thickness of said FM semi-fixed layer is selected to have in-plane (IP) and out-of-plane (OOP) anisotropies which are balanced between being nearly equal, and a preference plane of the FM fixed layer;
- wherein OOP anisotropy of said FM free layer is affected by the interface properties between the FM layers and said DE layer, and is controlled by voltages applied across said DE layer as an applied voltage, giving rise to a voltage-controlled magnetic anisotropy (VCMA) effect which rotates magnetization orientation of said FM free layer and is fully switched in response to a stray magnetic field from said FM semi-fixed and fixed layers, with state of the magnetic orientation determining bit state for said MeRAM;
- and
- wherein OOP anisotropy of said FM semi-fixed layer is affected by the interface properties between the FM layers and said DE layer, and is controlled by voltages applied across said DE layer as an applied voltage, giving rise to a voltage-controlled magnetic anisotropy (VCMA) effect which rotates magnetization orientation of said FM semi-fixed layer without fully switching its magnetic orientation.
8 more elements
A voltage-controlled magnetic anisotropy (VCMA) switch apparatus, comprising:
- at least two ferromagnetic (FM) layers having a FM fixed layer, and a FM free layer;
- and
- a dielectric (DE) layer interposed between said FM free layer and FM fixed layer;
- wherein material, shape and thickness of said FM free layer and said FM fixed layer are selected to have in-plane (IP) and out-of-plane (OOP) anisotropies;
- wherein material, shape and thickness of said FM free layer is selected to have in-plane (IP) and out-of-plane (OOP) anisotropies which are nearly equal;
- wherein said OOP anisotropy of said FM free layer is affected by interface properties between the FM layers and said DE layer, and is controlled by voltages applied across said DE layer as an applied voltage, giving rise to a voltage-controlled magnetic anisotropy (VCMA) effect which switches magnetization orientation of said FM free layer in said apparatus;
- and
- wherein said magnetization of said FM free layer is switched between two magnetization states comprising a magnetic domain wall, wherein said domain wall contains a large in-plane (IP) magnetization component.
5 more elements
A voltage-controlled magnetic anisotropy (VCMA) switch apparatus, comprising:
- a ferromagnetic (FM) fixed layer, of ferromagnetic material;
- a ferromagnetic (FM) free layer, of ferromagnetic material;
- a dielectric (DE) layer interposed between said FM free layer and FM fixed layer;
- and
- wherein material, shape and thickness of said FM free layer and said FM fixed layer are selected to have in-plane (IP) and out-of-plane (OOP) anisotropies;
- wherein material, shape and thickness of said FM free layer is selected to have in-plane (IP) and out-of-plane (OOP) anisotropies which are nearly equal;
- wherein said OOP anisotropy of said FM free layer is affected by interface properties between the FM layers and said DE layer, and is controlled by voltages applied across said DE layer as an applied voltage, giving rise to a voltage-controlled magnetic anisotropy (VCMA) effect which switches magnetization orientation of said FM free layer in said apparatus;
- and
- wherein thickness of said DE layer is selected to allow sufficient leakage current for determining a direction of switching based on a leakage-current induced magnetic torque in response to an applied voltage, while said leakage-current is insufficient for switching the magnetization state of said apparatus.
6 more elements
Dependencies are inferred from the claim text.